Journal articles: 'Supercritical Regime'

1

Robinet, J. C., and X. Gloerfelt. "Instabilities in non-ideal fluids." Journal of Fluid Mechanics 880 (October 4, 2019): 1–4. http://dx.doi.org/10.1017/jfm.2019.719.

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The recent study of Ren et al. (J. Fluid Mech., vol. 871, 2019, pp. 831–864) investigated the hydrodynamic linear stability of a compressible boundary layer over an insulated flat plate for a non-ideal gas (supercritical $\text{CO}_{2}$). In particular, the authors showed that in the transcritical regime (across the pseudo-critical line) the flow is strongly convectively unstable due to the co-existence of two unstable modes: Mode I, related to Tollmien–Schlichting instabilities and a new inviscid two-dimensional mode (Mode II) with a spatial growth rate one order of magnitude larger than Mode I for high Eckert numbers. In contrast to the transcritical regime, in the sub- and supercritical regimes, Mode II does not exist. Only Mode I drives the instabilities: viscous and two-dimensional for the subcritical regime and inflectional and three-dimensional for the supercritical regime.

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Azimi, Hamed, and Saeid Shabanlou. "Comparison of Subcritical and Supercritical Flow Patterns Within Triangular Channels Along the Side Weir." International Journal of Nonlinear Sciences and Numerical Simulation 17, no. 7-8 (December 1, 2016): 361–68. http://dx.doi.org/10.1515/ijnsns-2015-0103.

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AbstractSide weirs with triangular channel are used as flow controlling devices in draining and irrigation networks. By installing a side weir on the main conduits side walls, the runoff overflows from the weir and are conducted toward the diversion channel. In this study, changing of the flow free surface and the turbulence of the flow field in triangular channels with side weir are numerically simulated using volume of fluid (VOF) scheme and RNG k–ε turbulence model. In the present paper, the pattern of the spatially varied flow with decreasing discharge in both subcritical and supercritical flow regimes for triangular channels with side weirs was simulated. The present numerical model has precisely predicted the changes of the water surface and the specific energy. In subcritical regime, the flow depth is from the beginning of the weir toward its end is followed by an increase and in supercritical conditions is followed by a reduction in depth. For both subcritical and supercritical regimes, a drop in the surface in the first third of the weir’s opening and a surface jump in the final third of its length has occurred. Along the mentioned surface jump the amount of the kinetic energy increases and the potential energy reduces. According to results of the simulation, the maximum longitudinal velocity for subcritical flow regime occurs in the first third of the length of the side weir and for supercritical flow regime, almost in the middle of the weir opening happens. In both subcritical and supercritical regimes, the maximum transverse velocity has occurred in the final third of the length of the side weir.

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Celsus, Andrew F., and Guilherme L. F. Silva. "Supercritical regime for the kissing polynomials." Journal of Approximation Theory 255 (July 2020): 105408. http://dx.doi.org/10.1016/j.jat.2020.105408.

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Bozier, J. C., J. P. Le Breton, T. Jalinaud, and J. Valadon. "A New Supercritical Shock Wave Regime." Astrophysical Journal Supplement Series 127, no. 2 (April 2000): 253–60. http://dx.doi.org/10.1086/313363.

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Solodoch, Aviv, Jeroen M. Molemaker, Kaushik Srinivasan, Maristella Berta, Louis Marie, and Arjun Jagannathan. "Observations of Shoaling Density Current Regime Changes in Internal Wave Interactions." Journal of Physical Oceanography 50, no. 6 (June 1, 2020): 1733–51. http://dx.doi.org/10.1175/jpo-d-19-0176.1.

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AbstractWe present in situ and remote observations of a Mississippi plume front in the Louisiana Bight. The plume propagated freely across the bight, rather than as a coastal current. The observed cross-front circulation pattern is typical of density currents, as are the small width (≈100 m) of the plume front and the presence of surface frontal convergence. A comparison of observations with stratified density current theory is conducted. Additionally, subcritical to supercritical transitions of frontal propagation speed relative to internal gravity wave (IGW) speed are demonstrated to occur. That is in part due to IGW speed reduction with decrease in seabed depth during the frontal propagation toward the shore. Theoretical steady-state density current propagation speed is in good agreement with the observations in the critical and supercritical regimes but not in the inherently unsteady subcritical regime. The latter may be due to interaction of IGW with the front, an effect previously demonstrated only in laboratory and numerical experiments. In the critical regime, finite-amplitude IGWs form and remain locked to the front. A critical to supercritical transition eventually occurs as the ambient conditions change during frontal propagation, after which IGWs are not supported at the front. The subcritical (critical) to critical (supercritical) transition is related to Froude number ahead (under) the front, consistently with theory. Finally, we find that the front-locked IGW (critical) regime is itself dependent on significant nonlinear speed enhancement of the IGW by their growth to finite amplitude at the front.

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Ghayesh, Mergen H., and Hamed Farokhi. "Parametric instability of microbeams in supercritical regime." Nonlinear Dynamics 83, no. 3 (October 13, 2015): 1171–83. http://dx.doi.org/10.1007/s11071-015-2395-4.

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Wang, Di, Mian Chen, Yan Jin, and Andrew P. Bunger. "Effect of Fluid Compressibility on Toughness-Dominated Hydraulic Fractures With Leakoff." SPE Journal 23, no. 06 (September 26, 2018): 2118–32. http://dx.doi.org/10.2118/193995-pa.

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Summary Hydraulic fracturing using supercritical carbon dioxide (CO2) has a recognized potential to grow in importance for unconventional oil and gas reservoirs. It is characterized by higher compressibility than traditional liquid-phase hydraulic-fracturing fluids. Motivated by the larger compressibility of supercritical CO2, this paper considers the problem of a hydraulic fracture in which a compressible fluid is injected at a constant rate to drive a hydraulic fracture in a permeable and brittle rock. The two cases of a plane-strain fracture and a penny-shaped fracture are considered. It is shown that for many practical cases, the formation has a large enough fracture toughness that the propagation is in a regime for which the pressure inside the hydraulic fracture can be treated as spatially uniform (“toughness dominated”). Both numerical simulations and analytical solutions for the relevant limiting regimes show that fluid compressibility affects fracture shape only at the very beginning period, which corresponds to the storage regime, and has little effect on fracture growth in the leakoff regime. Overall, because the transition from the storage regime to the leakoff regime is expected to often take place in a short time after the fracture starts propagating, the influence of compressibility in the storage regime is very brief and can be quickly ignored. Therefore, even relatively sizable fluid compressibility has almost no effect on fracture growth in the toughness-dominated regime when leakoff is taken into account.

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Choi, Woocheol, Younghun Hong, and Jinmyoung Seok. "On critical and supercritical pseudo-relativistic nonlinear Schrödinger equations." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 150, no. 3 (January 30, 2019): 1241–63. http://dx.doi.org/10.1017/prm.2018.114.

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AbstractIn this paper, we investigate existence and non-existence of a nontrivial solution to the pseudo-relativistic nonlinear Schrödinger equation $$\left( \sqrt{-c^2\Delta + m^2 c^4}-mc^2\right) u + \mu u = \vert u \vert^{p-1}u\quad {\rm in}~{\open R}^n~(n \ges 2) $$ involving an H1/2-critical/supercritical power-type nonlinearity, that is, p ⩾ ((n + 1)/(n − 1)). We prove that in the non-relativistic regime, there exists a nontrivial solution provided that the nonlinearity is H1/2-critical/supercritical but it is H1-subcritical. On the other hand, we also show that there is no nontrivial bounded solution either (i) if the nonlinearity is H1/2-critical/supercritical in the ultra-relativistic regime or (ii) if the nonlinearity is H1-critical/supercritical in all cases.

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Temme, Franziska, Jenny V. Turton, Thomas Mölg, and Tobias Sauter. "Flow Regimes and Föhn Types Characterize the Local Climate of Southern Patagonia." Atmosphere 11, no. 9 (August 25, 2020): 899. http://dx.doi.org/10.3390/atmos11090899.

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The local climate in Southern Patagonia is strongly influenced by the interaction between the topography and persistent westerlies, which can generate föhn events, dry and warm downslope winds. The upstream flow regime influences different föhn types which dictate the lee-side atmospheric response regarding the strength, spatial extent and phenomenology. We use a combination of observations from four automatic weather stations (AWSs) and high-resolution numerical modeling with the Weather Research and Forecasting (WRF) model for a region in Southern Patagonia (48° S–52° S, 72° W–76.5° W) including the Southern Patagonian Icefield (SPI). The application of a föhn identification algorithm to a 10-month study period (June 2018–March 2019) reveals 81 föhn events in total. A simulation of three events of differing flow regimes (supercritical, subcritical, transition) suggests that a supercritical flow regime leads to a linear föhn event with a large spatial extent but moderate intensity. In contrast, a spatially limited but locally strong föhn response is induced by a subcritical regime with upstream blocking and by a transition regime with a hydraulic jump present. Our results imply that the hydraulic jump-type föhn event (transition case) is the most critical for glacier mass balances since it shows the strongest warming, drying, wind velocities and solar radiation over the SPI. The consideration of flow regimes over the last 40 years shows that subcritical flow occurs most frequently (78%), however transitional flow occurs 14% of the time, implying the potential impact on Patagonian glaciers.

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Postnov, Konstantin A., Alexander G. Kuranov, and Lev R. Yungelson. "X-ray binaries with neutron stars at different accretion stages." Proceedings of the International Astronomical Union 14, S346 (August 2018): 219–27. http://dx.doi.org/10.1017/s174392131900125x.

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Abstract. Different accretion regimes onto magnetized NSs in HMXBs are considered: wind-fed supersonic (Bondi) regime at high accretion rates <math/> g s-1, subsonic settling regime at lower <math/> and supercritical disc accretion during Roche lobe overflow. In wind-fed stage, NSs in HMXBs reach equilibrium spin periods P* proportional to binary orbital period Pb. At supercritical accretion stage, the system may appear as a pulsating ULX. Population synthesis of Galactic HMXBs using standard assumptions on the binary evolution and NS formation is presented. Comparison of the model P* – Pb (the Corbet diagram), P* – Lx and Pb – Lx distributions with those for the observed HMXBs (including Be X-ray binaries) and pulsating ULXs suggests the importance of the reduction of P* in non-circular orbits, explaining the location of Be X-ray binaries in the model Corbet diagram, and the universal parameters of pulsating ULXs depending only on the NS magnetic fields.

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Mandal, Manoj, and Sabyasachi Pal. "Study of timing and spectral properties of the X-ray pulsar 1A 0535+262 during the giant outburst in 2020 November–December." Monthly Notices of the Royal Astronomical Society 511, no. 1 (January 31, 2022): 1121–30. http://dx.doi.org/10.1093/mnras/stac111.

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ABSTRACT We made a detailed study of the timing and spectral properties of the X-ray pulsar 1A 0535+262 during the recent giant outburst in 2020 November and December. The flux of the pulsar reached a record value of ∼12.5 Crab as observed by Swift/BAT (15–50 keV) and the corresponding mass accretion rate was ∼6.67 × 1017 g s−1 near the peak of the outburst. There was a transition from the subcritical to the supercritical accretion regime which allows exploring different properties of the source in the supercritical regime. A q-like feature was detected in the hardness–intensity diagram during the outburst. We observed high variability and strong energy dependence of pulse profiles during the outburst. Cyclotron Resonant Scattering Feature (CRSF) was detected at ∼44 keV from the NuSTAR energy spectrum in the subcritical regime and the corresponding magnetic field was B ≃ 4.9 × 1012 G. The energy of the CRSF was shifted towards lower energy in the supercritical regime. The luminosity dependence of the CRSF was studied and during the supercritical regime, a negative correlation was observed between the line energy and luminosity. The critical luminosity was ∼6 × 1037erg s−1 above which a state transition occurred. A reversal of correlation between the photon index and luminosity was observed near the critical luminosity. The NuSTAR spectra can be described by a composite model with two continuum components, a blackbody emission, cut-off power law, and a discrete component to account for the iron emission line at 6.4 keV. An additional cyclotron absorption feature was included in the model.

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12

Ren, Jie, Song Fu, and Rene Pecnik. "Linear instability of Poiseuille flows with highly non-ideal fluids." Journal of Fluid Mechanics 859 (November 16, 2018): 89–125. http://dx.doi.org/10.1017/jfm.2018.815.

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The objective of this work is to investigate linear modal and algebraic instability in Poiseuille flows with fluids close to their vapour–liquid critical point. Close to this critical point, the ideal gas assumption does not hold and large non-ideal fluid behaviours occur. As a representative non-ideal fluid, we consider supercritical carbon dioxide ($\text{CO}_{2}$) at a pressure of 80 bar, which is above its critical pressure of 73.9 bar. The Poiseuille flow is characterized by the Reynolds number ($Re=\unicode[STIX]{x1D70C}_{w}^{\ast }u_{r}^{\ast }h^{\ast }/\unicode[STIX]{x1D707}_{w}^{\ast }$), the product of the Prandtl ($Pr=\unicode[STIX]{x1D707}_{w}^{\ast }C_{pw}^{\ast }/\unicode[STIX]{x1D705}_{w}^{\ast }$) and Eckert numbers ($Ec=u_{r}^{\ast 2}/C_{pw}^{\ast }T_{w}^{\ast }$) and the wall temperature that in addition to pressure determine the thermodynamic reference condition. For low Eckert numbers, the flow is essentially isothermal and no difference with the well-known stability behaviour of incompressible flows is observed. However, if the Eckert number increases, the viscous heating causes gradients of thermodynamic and transport properties, and non-ideal gas effects become significant. Three regimes of the laminar base flow can be considered: the subcritical (temperature in the channel is entirely below its pseudo-critical value), transcritical and supercritical temperature regimes. If compared to the linear stability of an ideal gas Poiseuille flow, we show that the base flow is modally more unstable in the subcritical regime, inviscid unstable in the transcritical regime and significantly more stable in the supercritical regime. Following the principle of corresponding states, we expect that qualitatively similar results will be obtained for other fluids at equivalent thermodynamic states.

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Arzel, Olivier, and Thierry Huck. "Contributions of Atmospheric Stochastic Forcing and Intrinsic Ocean Modes to North Atlantic Ocean Interdecadal Variability." Journal of Climate 33, no. 6 (March 15, 2020): 2351–70. http://dx.doi.org/10.1175/jcli-d-19-0522.1.

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AbstractAtmospheric stochastic forcing associated with the North Atlantic Oscillation (NAO) and intrinsic ocean modes associated with the large-scale baroclinic instability of the North Atlantic Current (NAC) are recognized as two strong paradigms for the existence of the Atlantic multidecadal oscillation (AMO). The degree to which each of these factors contribute to the low-frequency variability of the North Atlantic is the central question in this paper. This issue is addressed here using an ocean general circulation model run under a wide range of background conditions extending from a supercritical regime where the oceanic variability spontaneously develops in the absence of any atmospheric noise forcing to a damped regime where the variability requires some noise to appear. The answer to the question is captured by a single dimensionless number Γ measuring the ratio between the oceanic and atmospheric contributions, as inferred from the buoyancy variance budget of the western subpolar region. Using this diagnostic, about two-thirds of the sea surface temperature (SST) variance in the damped regime is shown to originate from atmospheric stochastic forcing whereas heat content is dominated by internal ocean dynamics. Stochastic wind stress forcing is shown to substantially increase the role played by damped ocean modes in the variability. The thermal structure of the variability is shown to differ fundamentally between the supercritical and damped regimes, with abrupt modifications around the transition between the two regimes. Ocean circulation changes are further shown to be unimportant for setting the pattern of SST variability in the damped regime but are fundamental for a preferred time scale to emerge.

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Mammadova, J. P., A. P. Abdullaev, R. M. Rzayev, R. F. Kelbaliev, S. H. Mammadova, and I. V. Musazade. "The study of temperature regimes of a pipe wall under turbulent regime and supercritical pressures." International Journal of Modern Physics B 34, no. 19 (July 27, 2020): 2050182. http://dx.doi.org/10.1142/s0217979220501829.

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The flow regimes of liquids encountered in engineering practice are mainly turbulent due to their structure, with which the features of such flows at supercritical pressure are considered in the work and some results are compared with similar ones obtained at low Reynolds numbers. Under these conditions, the physical properties of the fluid change sharply in the parietal layer and, depending on the values of the heat flux density and temperature, the area of sharp changes in physical properties can move along the flow cross section. Depending on the influence of these factors, the nature of the fluid flow can change, which affects the patterns of heat transfer and, accordingly, the nature of the distribution of wall temperature. In particular, conditions were identified for the appearance of a primary and secondary improved heat transfer regime. The possibility of the existence of an anomalous behavior of heat transfer during a turbulent flow of aromatic hydrocarbons was revealed, the nature of the distribution of the wall temperature along the length of the experimental tube is examined, and the influence of changes in the thermophysical properties of the substance on it is analyzed. The experimental data for water and toluene with a deteriorated heat transfer mode deviate from the calculated by [Formula: see text]25%. As is known, the flow regime of fluids in engineering practice is mainly turbulent in structure. Therefore, it is very important to study the characteristics of such flows at supercritical pressure and compare some results with similar results obtained at low Reynolds numbers.

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Simonnet, Eric. "Quantization of the Low-Frequency Variability of the Double-Gyre Circulation." Journal of Physical Oceanography 35, no. 11 (November 1, 2005): 2268–90. http://dx.doi.org/10.1175/jpo2806.1.

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Abstract The low-frequency dynamics of the double-gyre wind-driven circulation in large midlatitude oceanic basins is investigated. It is shown that for quasigeostrophic models linear (Rayleigh) friction is necessary to obtain realistic recirculation gyres and elongated jet streams with small meridional-to-zonal aspect ratio. It is also found that the use of either no-slip or free-slip boundary conditions does not change the drastic effects of bottom drag on the large scales. These long oceanic jets are alternatively destabilized and restabilized through successive (subcritical) supercritical symmetry-breaking bifurcations that are linked to the (non) existence of stationary Rossby waves. These waves are strongly localized along the oceanic front and are thus hardly affected by the basin geometry. Numerical and analytical results show that these waves are “quantized” with respect to the length of the jet, and an explicit dispersion relation is given. Numerical computations of branches of steady states, together with linear and nonlinear analysis, indicate that two classes of regimes characterize the low-frequency dynamics of the flow. The first class corresponds to supercritical regimes, which are associated with oceanic jets that have been destabilized by undamped stationary Rossby waves. In particular, these regimes allow the formation of gyre modes responsible for low-frequency relaxation oscillations of the jet. The second class corresponds to subcritical regimes, which are either quiescent or dominated by high-frequency instabilities and are characterized by jets that do not allow the formation of both stationary Rossby waves and gyre modes. Each of these regimes is characterized by typical spatial and time scales that are both quantized. The number n of “bumps” of the jet, which is related to the zonal wavenumber of the stationary Rossby waves, is used to distinguish between these regimes either in their supercritical or subcritical phase. For instance, the supercritical n = 2 regime is associated with a class of interdecadal gyre modes that extend up to 3000 km in the zonal direction. The quantization of the low-frequency dynamics and the existence of these regimes are also found to survive severe modifications of the basin geometry. These quantized regimes suggest that the low-frequency dynamics in turbulent regimes is likely to be autosimilar to the low-frequency dynamics found in a weakly nonlinear “ground” regime corresponding to n = 0.

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Azimi, Hamed, Saeid Shabanlou, Isa Ebtehaj, and Hossein Bonakdari. "Discharge Coefficient of Rectangular Side Weirs on Circular Channels." International Journal of Nonlinear Sciences and Numerical Simulation 17, no. 7-8 (December 1, 2016): 391–99. http://dx.doi.org/10.1515/ijnsns-2016-0033.

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AbstractIn this study, the flow turbulence and variations of the supercritical free surface flow in a circular channel along a side weir are simulated as three dimensional using the RNG k-ε turbulence model and volume of fluid (VOF) scheme. Comparison between the numerical model and experimental measurements shows that the numerical model simulates the free surface flow with good accuracy. According to the numerical model results, the specific energy variations along the side weir for the supercritical flow regime are almost constant and the energy drop is not significant but by increasing the side weir length the energy difference between the side weir upstream and downstream increases. Next, using the nonlinear regression (NLR) and analysis of the simulation results, some relationships for calculating the discharge coefficient of side weir on circular channels in supercritical flow regime are provided.

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TAO, TERENCE. "GLOBAL REGULARITY FOR A LOGARITHMICALLY SUPERCRITICAL DEFOCUSING NONLINEAR WAVE EQUATION FOR SPHERICALLY SYMMETRIC DATA." Journal of Hyperbolic Differential Equations 04, no. 02 (June 2007): 259–65. http://dx.doi.org/10.1142/s0219891607001124.

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We establish global regularity for the logarithmically energy-supercritical wave equation □u = u5 log (2 + u2) in three spatial dimensions for spherically symmetric initial data, by modifying an argument of Ginibre, Soffer and Velo for the energy-critical equation. This example demonstrates that critical regularity arguments can penetrate very slightly into the supercritical regime.

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Salinas, Jorge, S. Balachandar, Mrugesh Shringarpure, Juan Fedele, David Hoyal, and Mariano Cantero. "Soft transition between subcritical and supercritical currents through intermittent cascading interfacial instabilities." Proceedings of the National Academy of Sciences 117, no. 31 (July 20, 2020): 18278–84. http://dx.doi.org/10.1073/pnas.2008959117.

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Long-running gravity currents are flows that are submerged beneath a deep layer of quiescent fluid and they travel over long distances along inclined or horizontal surfaces. They are driven by the density difference between the current and the clear ambient fluid above. In this work we present results on highly resolved direct numerical simulations of turbid underflows that involve nearly 1 billion degrees of freedom. We assess the effect of bed slope on the flow statistics. We explore the turbulence dynamics of the interface in the classical sub- and supercritical regimes. We investigate the structure of interfacial turbulence and its relation to the turbulence statistic. A transcritical regime is identified where intermittent cascading interfacial instabilities appear. We investigate how departure from the self-sustaining equilibrium state may be the mechanism responsible for this cyclic evolution of the transcritical regime.

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Monakhov, V. N. "Stability of discrete dynamical systems in the supercritical regime." Doklady Mathematics 75, no. 2 (April 2007): 304–6. http://dx.doi.org/10.1134/s1064562407020330.

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Rutin, Sergey B., and Pavel V. Skripov. "Heat transfer in supercritical fluids under pulse heating regime." International Journal of Heat and Mass Transfer 57, no. 1 (January 2013): 126–30. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2012.10.027.

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Ding, Jian, Eyal Lubetzky, and Yuval Peres. "Anatomy of the giant component: The strictly supercritical regime." European Journal of Combinatorics 35 (January 2014): 155–68. http://dx.doi.org/10.1016/j.ejc.2013.06.004.

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Ding, Hu, and Li-Qun Chen. "Equilibria of axially moving beams in the supercritical regime." Archive of Applied Mechanics 81, no. 1 (November 7, 2009): 51–64. http://dx.doi.org/10.1007/s00419-009-0394-y.

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Ren, Jie, Olaf Marxen, and Rene Pecnik. "Boundary-layer stability of supercritical fluids in the vicinity of the Widom line." Journal of Fluid Mechanics 871 (May 28, 2019): 831–64. http://dx.doi.org/10.1017/jfm.2019.348.

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We investigate the hydrodynamic stability of compressible boundary layers over adiabatic walls with fluids at supercritical pressure in the proximity of the Widom line (also known as the pseudo-critical line). Depending on the free-stream temperature and the Eckert number that determines the viscous heating, the boundary-layer temperature profile can be either sub-, trans- or supercritical with respect to the pseudo-critical temperature, $T_{pc}$. When transitioning from sub- to supercritical temperatures, a seemingly continuous phase change from a compressible liquid to a dense vapour occurs, accompanied by highly non-ideal changes in thermophysical properties. Using linear stability theory (LST) and direct numerical simulations (DNS), several key features are observed. In the sub- and supercritical temperature regimes, the boundary layer is substantially stabilized the closer the free-stream temperature is to $T_{pc}$ and the higher the Eckert number. In the transcritical case, when the temperature profile crosses $T_{pc}$, the flow is significantly destabilized and a co-existence of dual unstable modes (Mode II in addition to Mode I) is found. For high Eckert numbers, the growth rate of Mode II is one order of magnitude larger than Mode I. An inviscid analysis shows that the newly observed Mode II cannot be attributed to Mack’s second mode (trapped acoustic waves), which is characteristic in high-speed boundary-layer flows with ideal gases. Furthermore, the generalized Rayleigh criterion (also applicable for non-ideal gases) unveils that, in contrast to the trans- and supercritical regimes, the subcritical regime does not contain an inviscid instability mechanism.

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Welahettige, Prasanna, Bernt Lie, and Knut Vaagsaether. "Flow regime changes at hydraulic jumps in an open Venturi channel for Newtonian fluid." Journal of Computational Multiphase Flows 9, no. 4 (July 31, 2017): 169–79. http://dx.doi.org/10.1177/1757482x17722890.

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The aim of this paper is to study flow regime changes of Newtonian fluid flow in an open Venturi channel. The simulations are based on the volume of fluid method with interface tracking. ANSYS Fluent 16.2 (commercial code) is used as the simulation tool. The simulation results are validated with experimental results. The experiments were conducted in an open Venturi channel with water at atmospheric condition. The inlet water flow rate was 400 kg/min. The flow depth was measured by using ultrasonic level sensors. Both experiment and simulation were done for the channel inclination angles 0°, −0.7°, and −1.5°. The agreement between computed and experimental results is satisfactory. At horizontal condition, flow in the channel is supercritical until contraction and subcritical after the contraction. There is a hydraulic jump separating the supercritical and subcritical flow. The position of the hydraulic jump oscillates within a region of about 100 mm. Hydraulic jumps coming from the contraction walls to the upstream flow are the main reasons for the conversion of supercritical flow into subcritical flow. An “oblique jump” can be seen where there is a supercritical flow in the contraction. There is a triple point in this oblique jump: the triple point consists of two hydraulic jumps coming from the contraction walls and the resultant wave. The highest flow depth and the lowest velocity in the triple point are found at the oblique jump.

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Zhou, Sha, Tian-Jun Yu, Xiao-Dong Yang, and Wei Zhang. "Global Dynamics of Pipes Conveying Pulsating Fluid in the Supercritical Regime." International Journal of Applied Mechanics 09, no. 02 (March 2017): 1750029. http://dx.doi.org/10.1142/s1758825117500296.

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Global dynamics of supercritical pipes conveying pulsating fluid considering superharmonic resonance of the second mode with 1:2 internal resonance are investigated. The governing partial differential equations in the supercritical regime are obtained based on the nontrivial equilibrium configuration of the pipes conveying fluid and then transformed into a discretized nonlinear gyroscopic system via assumed modes and Galerkin’s method. The method of multiple scales and canonical transformation are applied to reduce the equations of motion to the near-integrable Hamiltonian standard form. The energy-phase method is employed to demonstrate the existence of chaotic dynamics by identifying the existence of multi-pulse jumping orbits in the perturbed phase space. The global solutions are subsequently interpreted in terms of the physical motion of such gyroscopic system. Two types of nonlinear normal modal motion and the chaotic pattern conversion between the locked simple bidirectional traveling wave motion and the complex bidirectional traveling wave motion are discussed.

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Wong, C., and K. Kontis. "Pneumatic flow control studies using steady blowing on a supercritical aerofoil." Aeronautical Journal 113, no. 1139 (January 2009): 53–63. http://dx.doi.org/10.1017/s0001924000002773.

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Abstract Experimental studies have been conducted on a NASA 17-percent thick supercritical aerofoil with a Coanda trailing edge at subsonic speeds in both the boundary-layer control and circulation control regimes. Detailed boundary-layer surveys were performed along the mid span on the suction surface and around the Coanda trailing edge. The wake located at 43% chord-length behind the aerofoil was measured with a single-component hotwire anemometer, and the profile drag coefficients were calculated from the integration of wake momentum deficit. Lift forces and pitching moments were recorded from –20deg to +20deg incidence using a 3-component force balance. In the circulation control regime, the boundary-layer results indicated that separation bubbles are not present at high incidences compared to the boundary-layer control regime, and that minimised the potential for flow separation delay around the Coanda trailing edge. The spectral analysis of the wake showed a significant reduction of wake fluctuations at high incidences and improvement of the stability at the edge of the wake. The study of aerodynamic forces suggested the need to increase the blowing momentum coefficient if the circulation control is used near the stalling angle-of-attack.

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Palymskiy, I. B., V. I. Palymskiy, and I. V. Frolov. "Investigation of the characteristics of a heated plume rise in a gas." Interexpo GEO-Siberia 8, no. 1 (May 18, 2022): 155–65. http://dx.doi.org/10.33764/2618-981x-2022-8-1-155-166.

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The characteristics of an ascending heated plume in a compressible, viscous and heat-conducting gas are studied by numerical simulation. It is known that at the subcritical height of the region, the isobaric convection regime is realized, and at the supercritical one, adiabatic and superadiabatic. It is shown that adiabatic processes play a decisive role at the supercritical height of the region, and diffusion processes at the subcritical height.

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DING, JIAN, JEONG HAN KIM, EYAL LUBETZKY, and YUVAL PERES. "Diameters in Supercritical Random Graphs Via First Passage Percolation." Combinatorics, Probability and Computing 19, no. 5-6 (October 5, 2010): 729–51. http://dx.doi.org/10.1017/s0963548310000301.

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We study the diameter of 1, the largest component of the Erdős–Rényi random graph (n, p) in the emerging supercritical phase, i.e., for p = $\frac{1+\epsilon}n$ where ε3n → ∞ and ε = o(1). This parameter was extensively studied for fixed ε > 0, yet results for ε = o(1) outside the critical window were only obtained very recently. Prior to this work, Riordan and Wormald gave precise estimates on the diameter; however, these did not cover the entire supercritical regime (namely, when ε3n → ∞ arbitrarily slowly). Łuczak and Seierstad estimated its order throughout this regime, yet their upper and lower bounds differed by a factor of $\frac{1000}7$.We show that throughout the emerging supercritical phase, i.e., for any ε = o(1) with ε3n → ∞, the diameter of 1 is with high probability asymptotic to D(ε, n) = (3/ε)log(ε3n). This constitutes the first proof of the asymptotics of the diameter valid throughout this phase. The proof relies on a recent structure result for the supercritical giant component, which reduces the problem of estimating distances between its vertices to the study of passage times in first-passage percolation. The main advantage of our method is its flexibility. It also implies that in the emerging supercritical phase the diameter of the 2-core of 1 is w.h.p. asymptotic to $\frac23 D(\epsilon,n)$, and the maximal distance in 1 between any pair of kernel vertices is w.h.p. asymptotic to $\frac{5}9D(\epsilon,n)$.

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Wang, Qingyang, Xiaojing Ma, Jinliang Xu, Mingjia Li, and Yan Wang. "The three-regime-model for pseudo-boiling in supercritical pressure." International Journal of Heat and Mass Transfer 181 (December 2021): 121875. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2021.121875.

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Mignot, E., T. Moyne, D. Doppler, and N. Riviere. "Clear-Water Scouring Process in a Flow in Supercritical Regime." Journal of Hydraulic Engineering 142, no. 4 (April 2016): 04015063. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0001100.

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31

Zhang, Yan-Lei, and Li-Qun Chen. "Internal resonance of pipes conveying fluid in the supercritical regime." Nonlinear Dynamics 67, no. 2 (June 11, 2011): 1505–14. http://dx.doi.org/10.1007/s11071-011-0084-5.

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Middleton, Matthew J., Lucy Heil, Fabio Pintore, Dominic J. Walton, and Timothy P. Roberts. "A spectral-timing model for ULXs in the supercritical regime." Monthly Notices of the Royal Astronomical Society 447, no. 4 (January 16, 2015): 3243–63. http://dx.doi.org/10.1093/mnras/stu2644.

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TEKADE, SHRIKANT A., AVINASH D. VASUDEO, ANIRUDDHA D. GHARE, and RAMESH N. INGLE. "Measurement of flow in supercritical flow regime using cutthroat flumes." Sadhana 41, no. 2 (February 2016): 265–72. http://dx.doi.org/10.1007/s12046-016-0463-1.

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Sharma, Abhishek K., Manish K. Khandelwal, and P. Bera. "Finite amplitude analysis of non-isothermal parallel flow in a vertical channel filled with a highly permeable porous medium." Journal of Fluid Mechanics 857 (October 22, 2018): 469–507. http://dx.doi.org/10.1017/jfm.2018.745.

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This paper addresses the finite amplitude instability of stably stratified non-isothermal parallel flow in a vertical channel filled with a highly permeable porous medium. A cubic Landau equation is derived to study the limiting value of growth of instabilities under nonlinear effects. The non-Darcy model is considered to describe the flow instabilities in a porous medium. The nonlinear results are presented for air as well as water. The analysis is carried out in the vicinity of as well as away from the critical point (bifurcation point). It is found that when the medium is saturated by water then supercritical bifurcation is the only type of bifurcation at and beyond the bifurcation point. However, for air, depending on the strength of the flow and permeability of the medium, both supercritical and subcritical bifurcations are observed. The influence of nonlinear interaction of different harmonics on the heat transfer rate, friction coefficient, nonlinear kinetic energy spectrum and disturbance flow is also studied in both supercritical as well as subcritical regimes. The variation of neutral stability curves of parallel mixed convection flow of air with wavenumber reveals that a bifurcation that is supercritical for some wavenumber may be subcritical orvice versaat other nearby wavenumbers. The analysis of the nonlinear kinetic energy spectrum of the fundamental disturbance also supports the existence of supercritical/subcritical bifurcation at and away from the critical point. The effect of different harmonics on the pattern of secondary flow, based on linear stability theory, is also studied and a significant influence is found, especially in the subcritical regime.

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Khalilov, V. R., and I. V. Mamsurov. "Vacuum polarization of planar charged fermions with Coulomb and Aharonov–Bohm potentials." Modern Physics Letters A 31, no. 07 (March 2, 2016): 1650032. http://dx.doi.org/10.1142/s0217732316500322.

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Vacuum polarization of charged massless fermions is investigated in the superposition of Coulomb and Aharonov–Bohm (AB) potentials in 2 + 1 dimensions. For this purpose, we construct the Green function of the two-dimensional Dirac equation with Coulomb and AB potentials (via the regular and irregular solutions of the radial Dirac equation) and then calculate the vacuum polarization charge density in the so-called subcritical and supercritical regimes. In the supercritical regime, the Green function has a discontinuity in the complex plane of “energy” due to the singularities on the negative energy axis; these singularities are situated on the unphysical sheet and related to the creation of infinitely many quasistationary fermionic states with negative energies. We expect that our results will be helpful in gaining deeper understanding of the fundamental problem of quantum electrodynamics which can be applied to the problems of charged impurity screening in graphene taking into consideration the electron spin.

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Melville, W. K., and Karl R. Helfrich. "Transcritical two-layer flow over topography." Journal of Fluid Mechanics 178 (May 1987): 31–52. http://dx.doi.org/10.1017/s0022112087001101.

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The evolution of weakly-nonlinear two-layer flow over topography is considered. The governing equations are formulated to consider the effects of quadratic and cubic nonlinearity in the transcritical regime of the internal mode. In the absence of cubic nonlinearity an inhomogeneous Korteweg-de Vries equation describes the interfacial displacement. Numerical solutions of this equation exhibit undular bores or sequences of Boussinesq solitary waves upstream in a transcritical regime. For sufficiently large supercritical Froude numbers, a locally steady flow is attained over the topography. In that regime in which both quadratic and cubic nonlinearity are comparable, the evolution of the interface is described by an inhomogeneous extended Kortewegde Vries (EKdV) equation. This equation displays undular bores upstream in a subcritical regime, but monotonic bores in a transcritical regime. The monotonic bores are solitary wave solutions of the corresponding homogeneous EKdV equation. Again, locally steady flow is attained for sufficiently large supercritical Froude numbers. The predictions of the numerical solutions are compared with laboratory experiments which show good agreement with the solutions of the forced EKdV equation for some range of parameters. It is shown that a recent result of Miles (1986), which predicts an unsteady transcritical regime for single-layer flows, may readily be extended to two-layer flows (described by the forced KdV equation) and is in agreement with the results presented here.Numerical experiments exploiting the symmetry of the homogeneous EKdV equation show that solitary waves of fixed amplitude but arbitrary length may be generated in systems described by the inhomogeneous EKdV equation.

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Ramasamy, Dhanuskodi, Arunagiri Appusamy, and Anantharaman Narayanan. "Review of the Wall Temperature Prediction Capability of Available Correlations for Heat Transfer at Supercritical Conditions of Water." Journal of Energy 2013 (2013): 1–13. http://dx.doi.org/10.1155/2013/159098.

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The validity of the wall temperature predictions by 18 correlations available in the literature for supercritical heat-transfer regimes of water was verified for 12 experimental datasets consisting of 355 data points available in the literature. The correlations were ranked based on criteria like % data with <5% error, % data with <10°C error and minimum error band in temperature prediction. Details of the best fitting correlations were tabulated. The analysis indicated that for normal heat-transfer conditions, most of the correlations give close predictions. However, at deteriorated heat transfer regimes, only very few prediction points are closer to experimental value. Also, in the ranking process, the first position keeps varying, and no one correlation shall be said as the best for all experiments. Evaluation of the applicability of heat flux to mass-flux-ratio-based prediction of heat-transfer deterioration indicated 75% agreement. The empirical formulae linking mass flux for the prediction of the starting heat flux for heat-transfer deterioration indicated 58.33% of agreement. This review indicated that continued precise experimentation covering wide range of parameter conditions near pseudocritical regime and development of correlations is felt necessary for the accurate prediction of supercritical fluid heat transfer.

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Link, Oscar, Emmanuel Mignot, Sebastien Roux, Benoit Camenen, Cristián Escauriaza, Julien Chauchat, Wernher Brevis, and Salvatore Manfreda. "Scour at Bridge Foundations in Supercritical Flows: An Analysis of Knowledge Gaps." Water 11, no. 8 (August 10, 2019): 1656. http://dx.doi.org/10.3390/w11081656.

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The scour at bridge foundations caused by supercritical flows is reviewed and knowledge gaps are analyzed focusing on the flow and scour patterns, available measuring techniques for the laboratory and field, and physical and advanced numerical modeling techniques. Evidence suggests that the scour depth caused by supercritical flows is much smaller than expected, by an order of magnitude compared to that found in subcritical flows, although the reasons for this behavior remain still unclear. Important questions on the interaction of the horseshoe vortex with the detached hydraulic-jump and the wall-jet flow observed in supercritical flows arise, e.g., does the interaction between the flow structures enhance or debilitate the bed shear stresses caused by the horseshoe vortex? What is the effect of the Froude number of the incoming flow on the flow structures around the foundation and on the scour process? Recommendations are provided to develop and adapt research methods used in the subcritical flow regime for the study of more challenging supercritical flow cases.

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39

Lobov, N. I., and E. L. Tarunin. "Supercritical regime of convection in a vertical layer with moving walls." Fluid Dynamics 19, no. 5 (1985): 679–83. http://dx.doi.org/10.1007/bf01093531.

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Kuijlaars, A. B. J., and A. Tovbis. "The supercritical regime in the normal matrix model with cubic potential." Advances in Mathematics 283 (October 2015): 530–87. http://dx.doi.org/10.1016/j.aim.2015.06.020.

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41

Wu, Zhenqun, Hui Jin, Guobiao Ou, Liejin Guo, and Changqing Cao. "Three-dimensional numerical study on flow dynamics characteristics in supercritical water fluidized bed with consideration of real particle size distribution by computational particle fluid dynamics method." Advances in Mechanical Engineering 10, no. 6 (June 2018): 168781401877987. http://dx.doi.org/10.1177/1687814018779871.

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Supercritical water fluidized bed is a promising reactor which can realize the efficient and clean gasification of coal to produce hydrogen. As the high pressure and temperature inside supercritical water fluidized bed, the study of the detail flow behaviors needs the help of numerical method. Considering the limitation of the two-fluid method and discrete element method, the computational particle fluid dynamics method was applied to this work. When particle size distribution was taken into consideration, the simulated results showed that the transformation from fixed bed regime to fluidized bed regime is a gradual process. With the increase in superficial fluid velocity, particles in small diameter migrate to the top of the bed and there exits layering phenomenon in the bed. Besides, though the particles are categorized as Geldart B group, the minimum fluidization velocity is not equal to the minimum bubbling fluidization velocity and there is a complicated bed expansion process after incipient fluidization. The bed expansion process is also influenced by the particle size distribution.

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Bolotnova, R. Kh, and V. A. Korobchinskaya. "The study of the process of evolution of the jet under outflow of water from the supercritical state through a thin nozzle." Proceedings of the Mavlyutov Institute of Mechanics 11, no. 1 (2016): 66–71. http://dx.doi.org/10.21662/uim2016.1.010.

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The dynamics of the water outflow from the initial supercritical state through a thin nozzle is studied. To describe the initial stage of non-stationary process outflow the system of differential equations of conservation of mass, momentum and energy in a two-dimensional cylindrical coordinates with axial symmetry is used. The spatial distribution of pressure and velocity of jet formation was received. It was established that a supersonic regime of outflow at supercritical temperature of 650 K is formed, which have a qualitative agreement for the velocity compared with the Bernoulli analytical solution and the experimental data.

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Samoilova, Anna E., and Evelina V. Permyakova. "Nonlinear regimes of the steady Marangoni convection in a thin film heated from below." ВЕСТНИК ПЕРМСКОГО УНИВЕРСИТЕТА. ФИЗИКА, no. 1 (2022): 49–57. http://dx.doi.org/10.17072/1994-3598-2022-1-49-57.

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We investigate the dynamics of a thin liquid film that is placed atop a heated substrate of a very low thermal conductivity. The direct numerical simulation of the stationary long-wave Marangoni instability is performed within the system of coupled partial differential equations. These equations were previously derived within the lubrication approximation; they describe the evolution of film thickness and fluid temperature. We compare our results with previous results of the weakly-nonlinear analysis. A good qualitative agreement is observed for values of the Marangoni number near the instability threshold. In the case of supercritical excitation, our results for the amplitudes are described by the square root dependence on the supercriticality. In the case of subcritical excitation, we found the hysteresis. In the vicinity of the instability threshold the film interface is nearly sinusoidal, with two vortices under elevated region. As the supercriticality increases, the nonlinear stationary regimes arise, with a local elevation at the global minimum and with two additional vortices, correspondingly. In a case of subcritical excitation, relatively high supercriticality results in that these regimes evolve into film rupture via the emergence of secondary humps. For the supercritical excitation, stationary regime with doubled wavenumber occurs. We also revealed the transition through the traveling wave between two nonlinear regimes with different high of local humps.

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REEVES, BRANDON, ROBERT A. VAN GORDER, and S. ROY CHOUDHURY. "CHAOTIC REGIMES, POST-BIFURCATION DYNAMICS, AND COMPETITIVE MODES FOR A GENERALIZED DOUBLE HOPF NORMAL FORM." International Journal of Bifurcation and Chaos 22, no. 12 (December 2012): 1250292. http://dx.doi.org/10.1142/s0218127412502926.

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We discuss the post-bifurcation dynamics of the general double Hopf normal form, which allows us to study two intermittent routes to chaos (routes following either (i) subcritical or (ii) supercritical Hopf or double Hopf bifurcations). In particular, the route following supercritical bifurcations is somewhat subtle. Such behavior following repeated Hopf bifurcations is well-known and widely observed, including the classical Ruelle–Takens and quasiperiodic routes to chaos. However, it has not, to the best of our knowledge, been considered in the context of the double Hopf normal form, although it has been numerically observed and tracked in the post-double-Hopf regime. We then apply the method of competitive modes to verify parameter regimes for which the double Hopf normal form exhibits chaotic behavior. Such an analysis is useful, as it allows us to potentially identify specific parameter regimes for which the system may exhibit strange or irregular behavior, something which would be extremely difficult otherwise in a system with so many parameters. Indeed, it is conjectured that for parameter sets with two of the square-mode frequencies competitive or nearly competitive, chaotic behavior is likely to be observed in the system. We apply the method of competitive modes to two representative cases where intermittent chaos is found, and the competitive mode analysis there seems to verify the occurrence of chaos in each of the two types of regimes.

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JIANG, QINGFANG, and RONALD B. SMITH. "V-waves, bow shocks, and wakes in supercritical hydrostatic flow." Journal of Fluid Mechanics 406 (March 10, 2000): 27–53. http://dx.doi.org/10.1017/s0022112099007636.

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The structure of the bow shock, V-wave, and the related wave drag and wake in supercritical ambient flow are investigated for homogeneous hydrostatic single-layer flow with a free surface over an isolated two-dimensional (i.e. h(x, y)) obstacle. The two control parameters for this physical system are the ratio of obstacle height to fluid depth and the Froude number F = U/√gH. Based on theoretical analysis and numerical modelling, a steady-state regime diagram is constructed for supercritical flow. This study suggests that supercritical flow may have an upstream bow shock with a transition from the supercritical state to the subcritical state near the centreline, and a V-shock in the lee without a state transition. Unlike subcritical flow, neither a flank shock nor a normal lee shock is observed, due to the local supercritical environment. Both the bow shock and V-shock are dissipative and reduce the Bernoulli constant, but the vorticity generation is very weak in comparison with subcritical ambient flow. Thus, in supercritical flow, wakes are weak and eddy shedding is absent.Formulae for V-wave shape and V-wave drag are given using linear theory. Both formulae compare well with numerical model runs for small obstacles.These results can be applied to air flow over mountains, river hydraulics and coastal ocean currents with bottom topographies.

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MAMOU, M., P. VASSEUR, and E. BILGEN. "Double-diffusive convection instability in a vertical porous enclosure." Journal of Fluid Mechanics 368 (August 10, 1998): 263–89. http://dx.doi.org/10.1017/s0022112098001591.

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The Galerkin and the finite element methods are used to study the onset of the double-diffusive convective regime in a rectangular porous cavity. The two vertical walls of the cavity are subject to constant fluxes of heat and solute while the two horizontal ones are impermeable and adiabatic. The analysis deals with the particular situation where the buoyancy forces induced by the thermal and solutal effects are opposing each other and of equal intensity. For this situation, a steady rest state solution corresponding to a purely diffusive regime is possible. To demonstrate whether the solution is stable or unstable, a linear stability analysis is carried out to describe the oscillatory and the stationary instability in terms of the Lewis number, Le, normalized porosity, ε, and the enclosure aspect ratio, A. Using the Galerkin finite element method, it is shown that there exists a supercritical Rayleigh number, RsupTC, for the onset of the supercritical convection and an overstable Rayleigh number, RoverTC, at which overstability may arise. Furthermore, the overstable regime is shown to exist up to a critical Rayleigh number, RoscTC, at which the transition from the oscillatory to direct mode convection occurs. By using an analytical method based on the parallel flow approximation, the convective heat and mass transfer is studied. It is found that, below the supercritical Rayleigh number, RsupTC, there exists a subcritical Rayleigh number, RsubTC, at which a stable convective solution bifurcates from the rest state through finite-amplitude convection. In the range of the governing parameters considered in this study, a good agreement is observed between the analytical predictions and the finite element solution of the full governing equations. In addition, it is found that, for a given value of the governing parameters, the converged solution can be permanent or oscillatory, depending on the porous-medium porosity value, ε.

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47

Arutyunov, S. D., O. O. Yanushevich, A. M. Korsunsky, M. S. Podporin, А. I. Salimon, I. I. Romanenko, and V. N. Tsarev. "Carbon dioxide sterilization in critical/subcritical condition as an alternative to modern methods of eradication of bacteria, fungi and viruses on medical items (literature review)." Stomatology for All / International Dental review, no. 1(98) (March 22, 2022): 12–20. http://dx.doi.org/10.35556/idr-2022-1(98)12-22.

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Infections associated with the provision of medical care (ISMP) are a global problem that require the close attention of medical and preventive institutions. Therefore, strict compliance with the anti-infective safety regime, as well as the development of decontamination methods, materials and medical devices are an urgent approach to minimizing the risk of nosocomial infections. The purpose of the study is to provide an analytical assessment of the antimicrobial effectiveness of sterilization of medical materials and instruments with carbon dioxide in a supercritical and sub-supercritical state in comparison with other modern regulated methods of sterilization. Materials and methods. A meta-analysis of 1027 publications identified 67 publications, which are presented and analyzed in this literature review. Results and discussion. An updated review of experimental protocols based on supercritical sterilization and efficiency results sorted by strains of microorganisms and processed materials was carried out. The multidimensional effect of this sterilization method on microbial cells, spores, fungi and viruses is analyzed. Advantages and disadvantages in comparison with other sterilization technologies (autoclaving and its analogues, plasma sterilization, gamma rays) have been established conclusion. Conclusion. The use of carbon dioxide in supercritical/sub-supercritical states is a promising method that ensures high reliability of sterilization and the safety of processing objects.

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48

Arutyunov, S. D., O. O. Yanushevich, A. M. Korsunsky, M. S. Podporin, А. I. Salimon, I. I. Romanenko, and V. N. Tsarev. "Carbon dioxide sterilization in critical/subcritical condition as an alternative to modern methods of eradication of bacteria, fungi and viruses on medical items (literature review)." Stomatology for All / International Dental review, no. 1(98) (March 22, 2022): 12–20. http://dx.doi.org/10.35556/idr-2022-1(98)12-20.

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Infections associated with the provision of medical care (ISMP) are a global problem that require the close attention of medical and preventive institutions. Therefore, strict compliance with the anti-infective safety regime, as well as the development of decontamination methods, materials and medical devices are an urgent approach to minimizing the risk of nosocomial infections. The purpose of the study is to provide an analytical assessment of the antimicrobial effectiveness of sterilization of medical materials and instruments with carbon dioxide in a supercritical and sub-supercritical state in comparison with other modern regulated methods of sterilization. Materials and methods. A meta-analysis of 1027 publications identified 67 publications, which are presented and analyzed in this literature review. Results and discussion. An updated review of experimental protocols based on supercritical sterilization and efficiency results sorted by strains of microorganisms and processed materials was carried out. The multidimensional effect of this sterilization method on microbial cells, spores, fungi and viruses is analyzed. Advantages and disadvantages in comparison with other sterilization technologies (autoclaving and its analogues, plasma sterilization, gamma rays) have been established conclusion. Conclusion. The use of carbon dioxide in supercritical/sub-supercritical states is a promising method that ensures high reliability of sterilization and the safety of processing objects.

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Dembin, Barbara. "Regularity of the time constant for a supercritical Bernoulli percolation." ESAIM: Probability and Statistics 25 (2021): 109–32. http://dx.doi.org/10.1051/ps/2021005.

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We consider an i.i.d. supercritical bond percolation on ℤd, every edge is open with a probability p > pc(d), where pc(d) denotes the critical parameter for this percolation. We know that there exists almost surely a unique infinite open cluster 𝒞p. We are interested in the regularity properties of the chemical distance for supercritical Bernoulli percolation. The chemical distance between two points x, y ∈ 𝒞p corresponds to the length of the shortest path in 𝒞p joining the two points. The chemical distance between 0 and nx grows asymptotically like nμp(x). We aim to study the regularity properties of the map p → μp in the supercritical regime. This may be seen as a special case of first passage percolation where the distribution of the passage time is Gp = pδ1 + (1 − p)δ∞, p > pc(d). It is already known that the map p → μp is continuous.

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Eichelberger, John, Alexey Kiryukhin, Silvio Mollo, Noriyoshi Tsuchiya, and Marlène Villeneuve. "Exploring and Modeling the Magma–Hydrothermal Regime." Geosciences 10, no. 6 (June 18, 2020): 234. http://dx.doi.org/10.3390/geosciences10060234.

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This special issue comprises 12 papers from authors in 10 countries with new insights on the close coupling between magma as an energy and fluid source with hydrothermal systems as a primary control of magmatic behavior. Data and interpretation are provided on the rise of magma through a hydrothermal system, the relative timing of magmatic and hydrothermal events, the temporal evolution of supercritical aqueous fluids associated with ore formation, the magmatic and meteoric contributions of water to the systems, the big picture for the highly active Krafla Caldera, Iceland, as well as the implications of results from drilling at Krafla concerning the magma–hydrothermal boundary. Some of the more provocative concepts are that magma can intrude a hydrothermal system silently, that coplanar and coeval seismic events signal “magma fracking” beneath active volcanoes, that intrusive accumulations may far outlast volcanism, that arid climate favors formation of large magma chambers, and that even relatively dry rhyolite magma can convect rapidly and so lack a crystallizing mush roof. A shared theme is that hydrothermal and magmatic reservoirs need to be treated as a single system.

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Journal articles on the topic 'Supercritical Regime'

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