Journal articles: 'Transferts advectifs'

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Genuchten, Martinus Th van, Feike J. Leij, Todd H. Skaggs, Nobuo Toride, Scott A. Bradford, and Elizabeth M. Pontedeiro. "Exact Analytical Solutions for Contaminant Transport in Rivers." Journal of Hydrology and Hydromechanics 61, no. 3 (September 1, 2013): 250–59. http://dx.doi.org/10.2478/johh-2013-0032.

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Abstract Contaminant transport processes in streams, rivers, and other surface water bodies can be analyzed or predicted using the advection-dispersion equation and related transport models. In part 1 of this two-part series we presented a large number of one- and multi-dimensional analytical solutions of the standard equilibrium advection-dispersion equation (ADE) with and without terms accounting for zero-order production and first-order decay. The solutions are extended in the current part 2 to advective-dispersive transport with simultaneous first-order mass exchange between the stream or river and zones with dead water (transient storage models), and to problems involving longitudinal advectivedispersive transport with simultaneous diffusion in fluvial sediments or near-stream subsurface regions comprising a hyporheic zone. Part 2 also provides solutions for one-dimensional advective-dispersive transport of contaminants subject to consecutive decay chain reactions.

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Genuchten, Martinus Th van, Feike J. Leij, Todd H. Skaggs, Nobuo Toride, Scott A. Bradford, and Elizabeth M. Pontedeiro. "Exact analytical solutions for contaminant transport in rivers 1. The equilibrium advection-dispersion equation." Journal of Hydrology and Hydromechanics 61, no. 2 (June 1, 2013): 146–60. http://dx.doi.org/10.2478/johh-2013-0020.

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Abstract Analytical solutions of the advection-dispersion equation and related models are indispensable for predicting or analyzing contaminant transport processes in streams and rivers, as well as in other surface water bodies. Many useful analytical solutions originated in disciplines other than surface-water hydrology, are scattered across the literature, and not always well known. In this two-part series we provide a discussion of the advection-dispersion equation and related models for predicting concentration distributions as a function of time and distance, and compile in one place a large number of analytical solutions. In the current part 1 we present a series of one- and multi-dimensional solutions of the standard equilibrium advection-dispersion equation with and without terms accounting for zero-order production and first-order decay. The solutions may prove useful for simplified analyses of contaminant transport in surface water, and for mathematical verification of more comprehensive numerical transport models. Part 2 provides solutions for advective- dispersive transport with mass exchange into dead zones, diffusion in hyporheic zones, and consecutive decay chain reactions.

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Peyrillé, Philippe, and Jean-Philippe Lafore. "An Idealized Two-Dimensional Framework to Study the West African Monsoon. Part II: Large-Scale Advection and the Diurnal Cycle." Journal of the Atmospheric Sciences 64, no. 8 (August 2007): 2783–803. http://dx.doi.org/10.1175/jas4052.1.

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The idealized 2D model developed in Part I of this study is used to study the West African monsoon sensitivity to large-scale forcing. Using ECWMF reanalyses, a large-scale forcing is introduced in the 2D model in terms of temperature and humidity advection. A coherent structure of cooling–moistening near the surface and drying–warming in the 2–4-km layer is found in the Saharan heat low region. The effect of the advective forcing is to block the monsoon propagation by strengthening the northerly flux and by an increase of convective inhibition. The heat low thus appears to play a key role in the monsoon northward penetration through its temperature and humidity budget. Ultimately, warmer low levels and/or more moist midlevels in the heat low favor a more northerly position of the ITCZ. A detailed view of the continental diurnal cycle is also presented. Potential temperature and humidity budgets are performed in the deep convective and heat low area. The moistening process to sustain deep convection is made through nocturnal advection at low levels and daytime turbulence that redistributes humidity vertically. The same mechanism occurs in the heat low except that the vertical transfers by turbulence help maintain the dryness of the low levels. A possible mechanism of interaction between the deep convective zone and the Saharan heat low is also proposed that involves gravity waves in the upper troposphere.

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Aderogba, Adebayo Abiodun, and Appanah Rao Appadu. "Classical and Multisymplectic Schemes for Linearized KdV Equation: Numerical Results and Dispersion Analysis." Fluids 6, no. 6 (June 8, 2021): 214. http://dx.doi.org/10.3390/fluids6060214.

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We construct three finite difference methods to solve a linearized Korteweg–de-Vries (KdV) equation with advective and dispersive terms and specified initial and boundary conditions. Two numerical experiments are considered; case 1 is when the coefficient of advection is greater than the coefficient of dispersion, while case 2 is when the coefficient of dispersion is greater than the coefficient of advection. The three finite difference methods constructed include classical, multisymplectic and a modified explicit scheme. We obtain the stability region and study the consistency and dispersion properties of the various finite difference methods for the two cases. This is one of the rare papers that analyse dispersive properties of methods for dispersive partial differential equations. The performance of the schemes are gauged over short and long propagation times. Absolute and relative errors are computed at a given time at the spatial nodes used.

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Sun, Yubiao, Amitesh S. Jayaraman, and Gregory S. Chirikjian. "Approximate solutions of the advection–diffusion equation for spatially variable flows." Physics of Fluids 34, no. 3 (March 2022): 033318. http://dx.doi.org/10.1063/5.0084789.

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The advection–diffusion equation (ADE) describes many important processes in hydrogeology, mechanics, geology, and biology. The equations model the transport of a passive scalar quantity in a flow. In this paper, we have developed a new approach to solve incompressible advection–diffusion equations (ADEs) with variable convective terms, which are essential to study species transport in various flow scenarios. We first reinterpret advection diffusion equations on a microscopic level and obtain stochastic differential equations governing the behavior of individual particles of the species transported by the flow. Then, simplified versions of ADEs are derived to approximate the original ADEs governing concentration evolution of species. The approximation is effectively a linearization of the spatially varying coefficient of the advective term. These simplified equations are solved analytically using the Fourier transform. We have validated this new method by comparing our results to solutions obtained from the canonical stochastic sampling method and the finite element method. This mesh-free algorithm achieves comparable accuracy to the results from discrete stochastic simulation of spatially resolved species transport in a Lagrangian frame of reference. The good consistency shows that our proposed method is efficient in simulating chemical transport in a convective flow. The proposed method is computationally efficient and quantitatively reliable, providing an alternative technique to investigate various advection–diffusion processes.

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Dritschel, David G., and Maarten H. P. Ambaum. "The Diabatic Contour Advective Semi-Lagrangian Model." Monthly Weather Review 134, no. 9 (September 1, 2006): 2503–14. http://dx.doi.org/10.1175/mwr3202.1.

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Abstract This article describes a novel algorithmic development extending the contour advective semi-Lagrangian model to include nonconservative effects. The Lagrangian contour representation of finescale tracer fields, such as potential vorticity, allows for conservative, nondiffusive treatment of sharp gradients allowing very high numerical Reynolds numbers. It has been widely employed in accurate geostrophic turbulence and tracer advection simulations. In the present, diabatic version of the model the constraint of conservative dynamics is overcome by including a parallel Eulerian field that absorbs the nonconservative (diabatic) tendencies. The diabatic buildup in this Eulerian field is limited through regular, controlled transfers of this field to the contour representation. This transfer is done with a fast newly developed contouring algorithm. This model has been implemented for several idealized geometries. In this paper a single-layer doubly periodic geometry is used to demonstrate the validity of the model. The present model converges faster than the analogous semi-Lagrangian models at increased resolutions. At the same nominal spatial resolution the new model is 40 times faster than the analogous semi-Lagrangian model. Results of an orographically forced idealized storm track show nontrivial dependency of storm-track statistics on resolution and on the numerical model employed. If this result is more generally applicable, this may have important consequences for future high-resolution climate modeling.

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Surfleet, Christopher, and Justin Louen. "The Influence of Hyporheic Exchange on Water Temperatures in a Headwater Stream." Water 10, no. 11 (November 9, 2018): 1615. http://dx.doi.org/10.3390/w10111615.

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A headwater stream in coastal California was used to evaluate the temperature response of effective shade reduction. Spatial distribution of stream water temperatures for summer low-flow conditions (<0.006 m3 s−1) were highly correlated with net radiation and advective heat transfers from hyporheic exchange and subsequent streambed conduction. Using a heat budget model, mean maximum stream water temperatures were predicted to increase by 1.7 to 2.2 °C for 50% and 0% effective shade scenarios, respectively, at the downstream end of a 300 m treatment reach. Effects on mean maximum stream water temperature changes, as water flowed downstream through a 500 m shaded reach below the treatment reach, were reduced by 52 to 30% from the expected maximum temperature increases under the 50% and 0% effective shade scenarios, respectively. Maximum stream water temperature change predicted by net radiation heating alone was greater than measured and heat-budget-estimated temperatures. When the influence of hyporheic water exchange was combined with net radiation predictions, predicted temperatures were similar to measured and heat-budget-predicted temperatures. Results indicate that advective heat transfers associated with hyporheic exchange can promote downstream cooling following stream water temperature increases from shade reduction in a headwater stream with cascade, step-pool, and large woody debris forced-pool morphology.

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Lumpkin, Rick, and Kevin Speer. "Global Ocean Meridional Overturning." Journal of Physical Oceanography 37, no. 10 (October 1, 2007): 2550–62. http://dx.doi.org/10.1175/jpo3130.1.

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Abstract A decade-mean global ocean circulation is estimated using inverse techniques, incorporating air–sea fluxes of heat and freshwater, recent hydrographic sections, and direct current measurements. This information is used to determine mass, heat, freshwater, and other chemical transports, and to constrain boundary currents and dense overflows. The 18 boxes defined by these sections are divided into 45 isopycnal (neutral density) layers. Diapycnal transfers within the boxes are allowed, representing advective fluxes and mixing processes. Air–sea fluxes at the surface produce transfers between outcropping layers. The model obtains a global overturning circulation consistent with the various observations, revealing two global-scale meridional circulation cells: an upper cell, with sinking in the Arctic and subarctic regions and upwelling in the Southern Ocean, and a lower cell, with sinking around the Antarctic continent and abyssal upwelling mainly below the crests of the major bathymetric ridges.

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Ménesguen, C., S. Le Gentil, P. Marchesiello, and N. Ducousso. "Destabilization of an Oceanic Meddy-Like Vortex: Energy Transfers and Significance of Numerical Settings." Journal of Physical Oceanography 48, no. 5 (May 2018): 1151–68. http://dx.doi.org/10.1175/jpo-d-17-0126.1.

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Abstract The increase of computational capabilities led recent studies to implement very high-resolution simulations that gave access to new scale interaction processes, particularly those associated with the transfer of energy from the oceanic mesoscales to smaller scales through an interior route to dissipation, which is still underexplored. In this context, we study spindown simulations of a mesoscale interior vortex, unstable to a mixed baroclinic–barotropic instability. Even though the global energy is almost conserved, some energy is transferred down to dissipation scales during the development of instabilities. However, in our parameter regime, there is no substantial forward energy cascade sustained by unbalanced dynamics. Rather than exploring the physical parameter range, we clarify numerical discretization issues that can be detrimental to the physical solutions and our interpretation of finescale dynamics. Special care is given to determining the effective resolution of the different simulations. We improve it by a factor of 2 in our primitive equation (PE) finite-difference Coastal and Regional Ocean Community (CROCO) model by implementing a fifth-order accurate horizontal advection scheme. We also explore a range of grid aspect ratios dx/dz and find that energy spectra converge for aspect ratios that are close to N/f, the ratio of the stratification N over the Coriolis parameter f. However, convergence is not reached in the PE model when using a fourth-order centered scheme for vertical tracer advection (standard in ROMS-family codes). The scheme produces dispersion errors that trigger baroclinic instabilities and generate spurious submesoscale horizontal features. This spurious instability shows great impact on submesoscale production and energy cascade, emphasizing the significance of numerical settings in oceanic turbulence studies.

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Gutknecht, E., I. Dadou, B. Le Vu, G. Cambon, J. Sudre, V. Garçon, E. Machu, et al. "Nitrogen transfers and air-sea N<sub>2</sub>O fluxes in the upwelling off Namibia within the oxygen minimum zone: a 3-D model approach." Biogeosciences Discussions 8, no. 2 (April 4, 2011): 3537–618. http://dx.doi.org/10.5194/bgd-8-3537-2011.

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Abstract. As regions of high primary production and being often associated to Oxygen Minimum Zones (OMZs), Eastern Boundary Upwelling Systems (EBUS) represent key regions for the oceanic nitrogen (N) cycle. Indeed, by exporting the Organic Matter (OM) and nutrients produced in the coastal region to the open ocean, EBUS can play an important role in sustaining primary production in subtropical gyres. Losses of fixed inorganic N, through denitrification and anammox processes and through nitrous oxide (N2O) emissions to the atmosphere, take place in oxygen depleted environments such as EBUS, and alleviate the role of these regions as a source of N. In the present study, we developed a 3-D coupled physical/biogeochemical (ROMS/BioBUS) model for investigating the full N budget in the Namibian sub-system of the Benguela Upwelling System (BUS). The different state variables of a climatological experiment have been compared to different data sets (satellite and in situ observations) and show that the model is able to represent this biogeochemical oceanic region. The N transfer is investigated in the Namibian upwelling system using this coupled model, especially in the Walvis Bay area between 22° S and 24° S where the OMZ is well developed (O2 < 0.5 ml O2 l−1). The upwelling process advects 24.2 × 1010 mol N yr−1 of nitrate enriched waters over the first 100 m over the slope and over the continental shelf. The meridional advection by the alongshore Benguela current brings also nutrient-rich waters with 21.1 × 1010 mol N yr−1. 10.5 × 1010 mol N yr−1 of OM are exported outside of the continental shelf (between 0 and 100-m depth). 32.4% and 18.1% of this OM are exported by advection in the form of Dissolved and Particulate Organic Matters (DOM and POM), respectively, however vertical sinking of POM represents the main contributor (49.5%) to OM export outside of the first 100-m depth of the water column on the continental shelf. The continental slope also represents a net N export (11.1 × 1010 mol N yr−1) between 0 and 100-m depth: advection processes export 14.4% of DOM and 1.8% of POM, and vertical sinking of POM contributes to 83.8%. Between 100 and 600-m depth, water column denitrification and anammox constitute a fixed inorganic N loss of 2.2 × 108 mol N yr−1 on the continental shelf and slope, which will not significantly influence the N transfer from the coast to the open ocean. At the bottom, an important quantity of OM is sequestrated in the upper sediments of the Walvis Bay area. 78.8% of POM vertical sinking at 100-m depth is sequestrated on the shelf sediment. Only 14% of POM vertical sinking reaches the sediment on the slope without being remineralized. From our estimation, the Walvis Bay area (0–100 m), can be a substantial N source (28.7 × 1010 mol N yr−1) for the eastern part of the South Atlantic Subtropical Gyre. Assuming the same area for the South Atlantic Subtropical Gyre as the North Atlantic Subtropical Gyre, this estimation is equivalent to 3.7 × 10−2 mol N m−2 yr−1 for the Walvis Bay area, and 0.38 mol N m−2 yr−1 by extrapolating for the entire Benguela upwelling system. This last estimation is of the same order as other possible N sources sustaining primary production in the subtropical gyres. The continental shelf off Walvis Bay area does not represent more than 1.2% of the world's major eastern boundary regions and 0.006% of the global ocean, its estimated N2O emission (2.9 × 108 mol N2O yr−1), using a parameterization based on oxygen consumption, contributes to 4% of the emissions in the eastern boundary regions, and represents 0.2% of global ocean N2O emission. Hence, even if the Walvis Bay area is a small domain, its N2O emissions have to be taken into account in the atmospheric N2O budget.

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Shah, Rehan Ali, Aamir Khan, and Amjad Ali. "Parametric analysis of magnetic field-dependent viscosity and advection–diffusion between rotating discs." Advanced Composites Letters 29 (January 1, 2020): 2633366X1989637. http://dx.doi.org/10.1177/2633366x19896373.

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The constitutive expressions of unsteady Newtonian fluid are employed in the mathematical formulation to model the flow between the circular space of porous and contracting discs. The flow behavior is investigated for magnetic field-dependent (MFD) viscosity and heat/mass transfers under the influence of a variable magnetic field. The equation for conservation of mass, modified Navier–Stokes, Maxwell, advection diffusion and transport equations are coupled as a system of ordinary differential equations. The expressions for torques and magnetohydrodynamic pressure gradient equation are derived. The MFD viscosity [Formula: see text], magnetic Reynolds number [Formula: see text], squeezing Reynolds number [Formula: see text], rotational Reynolds number [Formula: see text], magnetic field components [Formula: see text], [Formula: see text], pressure [Formula: see text] and the torques [Formula: see text], [Formula: see text] which the fluid exerts on discs are discussed through numerical results and graphical aids. It is concluded that magnetic Reynolds number causes an increase in magnetic field distributions and decrease in tangential velocity of flow field, also the fluid temperature is decreasing with increase in magnetic Reynolds number. The azimuthal and axial components of magnetic field have opposite behavior with increase in MFD viscosity.

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Delgado, João M. P. Q., and M. Vázquez da Silva. "Mass Transfer around a Sphere Buried in a Packed Bed." Defect and Diffusion Forum 353 (May 2014): 306–10. http://dx.doi.org/10.4028/www.scientific.net/ddf.353.306.

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The transport phenomenon of mass transfers between a moving fluid and a reacting sphere buried in a packed bed, with “uniform velocity”, was analysed numerically, for solute transport by both advection and diffusion to obtain the concentration field and, from it, the dimensionless concentration boundary layer thickness, , for , and . The bed of inert particles is taken to have uniform voidage. For this purpose, numerical solutions of the partial differential equations describing mass concentration of the solute were undertaken to obtain the concentration boundary layer thickness as a function of the relevant parameters. Finally, mathematical expressions that relate the dependence with the Peclet number and inert particle diameter are proposed to describe the approximate size of the concentration boundary layer thickness.

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Lane-Serff, G. F., and S. D. Sandbach. "Emptying non-adiabatic filling boxes: the effects of heat transfers on the fluid dynamics of natural ventilation." Journal of Fluid Mechanics 701 (May 23, 2012): 386–406. http://dx.doi.org/10.1017/jfm.2012.164.

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AbstractA model for steady flow in a ventilated space containing a heat source is developed, taking account of the main heat transfers at the upper and lower boundaries. The space has an opening at low level, allowing cool ambient air to enter the space, and an opening near the ceiling, allowing warm air to leave the space. The flow is driven by the temperature contrast between the air inside and outside the space (natural ventilation). Conductive heat transfer through the ceiling and radiant heat transfer from the ceiling to the floor are incorporated into the model, to investigate how these heat transports affect the flow and temperature distribution within the space. In the steady state, a layer of warm air occupies the upper part of the space, with the lower part of the space filled with cooler air (although this is warmer than the ambient air when the radiant transfer from ceiling to floor is included). Suitable scales are derived for the heat transfers, so that their relative importance can be characterized. Explicit relationships are found between the height of the interface, the opening area and the relative size of the heat transfers. Increasing heat conduction leads to a lowering of the interface height, while the inclusion of the radiant transfer tends to increase the interface height. Both of these effects are relatively small, but the effect on the temperatures of the layers is significant. Conductive heat transfer through the upper boundary leads to a significant lowering of the temperature in the space as a proportion of the injected heat flux is taken out of the space by conduction rather than advection. Radiative transfer from the ceiling to floor results in the lower layer becoming warmer than the ambient air. The results of the model are compared with full-scale laboratory results and a more complex unsteady model, and are shown to give results that are much more accurate than models which ignore the heat transfers.

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Joseph, Binson. "Chaotic advection by Rossby-Haurwitz waves." Fluid Dynamics Research 18, no. 1 (June 1996): 1–16. http://dx.doi.org/10.1016/0169-5983(96)80463-1.

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Sanchez-Roman, Antonio, Gabriel Jorda, Gianmaria Sannino, and Damia Gomis. "Modelling study of transformations of the exchange flows along the Strait of Gibraltar." Ocean Science 14, no. 6 (December 18, 2018): 1547–66. http://dx.doi.org/10.5194/os-14-1547-2018.

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Abstract. Vertical transfers of heat, salt and mass between the inflowing and outflowing layers at the Strait of Gibraltar are explored basing on the outputs of a three-dimensional fully nonlinear numerical model. The model covers the entire Mediterranean basin and has a very high spatial resolution around the strait (1/200∘). Another distinctive feature of the model is that it includes a realistic barotropic tidal forcing (diurnal and semi-diurnal), in addition to atmospheric pressure and heat and water surface fluxes. The results show a significant transformation of the properties of the inflowing and outflowing water masses along their path through the strait. This transformation is mainly induced by the recirculation of water, and therefore of heat and salt, between the inflowing and outflowing layers. The underlying process seems to be the hydraulic control acting at the Espartel section, Camarinal Sill and Tarifa Narrows, which limits the amount of water that can cross the sections and forces a vertical recirculation. This results in a complex spatio-temporal pattern of vertical transfers, with the sign of the net vertical transfer being opposite in each side of the Camarinal Sill. Conversely, the mixing seems to have little influence on the heat and salt exchanged between layers (∼2 %–10 % of advected heat and salt). Therefore, the main point of our work is that most of the transformation of water properties along the strait is induced by the vertical advection of heat and salt and not by vertical mixing. A simple relationship between the net flux and the vertical transfers of water, heat and salt is also proposed. This relationship could be used for the fine-tuning of coarse-resolution model parameterizations in the strait.

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CAPET, XAVIER, PATRICE KLEIN, BACH LIEN HUA, GUILLAUME LAPEYRE, and JAMES C. MCWILLIAMS. "Surface kinetic energy transfer in surface quasi-geostrophic flows." Journal of Fluid Mechanics 604 (May 14, 2008): 165–74. http://dx.doi.org/10.1017/s0022112008001110.

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The relevance of surface quasi-geostrophic dynamics (SQG) to the upper ocean and the atmospheric tropopause has been recently demonstrated in a wide range of conditions. Within this context, the properties of SQG in terms of kinetic energy (KE) transfers at the surface are revisited and further explored. Two well-known and important properties of SQG characterize the surface dynamics: (i) the identity between surface velocity and density spectra (when appropriately scaled) and (ii) the existence of a forward cascade for surface density variance. Here we show numerically and analytically that (i) and (ii) do not imply a forward cascade of surface KE (through the advection term in the KE budget). On the contrary, advection by the geostrophic flow primarily induces an inverse cascade of surface KE on a large range of scales. This spectral flux is locally compensated by a KE source that is related to surface frontogenesis. The subsequent spectral budget resembles those exhibited by more complex systems (primitive equations or Boussinesq models) and observations, which strengthens the relevance of SQG for the description of ocean/atmosphere dynamics near vertical boundaries. The main weakness of SQG however is in the small-scale range (scales smaller than 20–30 km in the ocean) where it poorly represents the forward KE cascade observed in non-QG numerical simulations.

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Belmadani, Ali, Pierre-Amaël Auger, Nikolai Maximenko, Katherine Gomez, and Sophie Cravatte. "Similarities and Contrasts in Time-Mean Striated Surface Tracers in Pacific Eastern Boundary Upwelling Systems: The Role of Ocean Currents in Their Generation." Fluids 6, no. 12 (December 15, 2021): 455. http://dx.doi.org/10.3390/fluids6120455.

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Eastern boundary upwelling systems feature strong zonal gradients of physical and biological properties between cool, productive coastal oceans and warm, oligotrophic subtropical gyres. Zonal currents and jets (striations) are therefore likely to contribute to the transport of water properties between coastal and open oceanic regions. For the first time, multi-sensor satellite data are used to characterize the time-mean signatures of striations in sea surface temperature (SST), salinity (SSS), and chlorophyll-a (Chl-a) in subtropical eastern North/South Pacific (ENP/ESP) upwelling systems. In the ENP, tracers exhibit striated patterns extending up to ~2500 km offshore. Striated signals in SST and SSS are highly correlated with quasi-zonal jets, suggesting that these jets contribute to SST/SSS mesoscale patterns via zonal advection. Striated Chl-a anomalies are collocated with sea surface height (SSH) bands, a possible result of mesoscale eddy trains trapping nutrients and forming striated signals. In the ESP, the signature of striations is only found in SST and coincides with the SSH bands, consistently with quasi-zonal jets located outside major zonal tracer gradients. An interplay between large-scale SST/SSS advection by the quasi-zonal jets, mesoscale SST/SSS advection by the large-scale meridional flow, and eddy advection may explain the persistent ENP hydrographic signature of striations. These results underline the importance of quasi-zonal jets for surface tracer structuring at the mesoscale.

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Habchi, Charbel, Thierry Lemenand, Dominique Della Valle, and Hassan Peerhossaini. "Liquid/liquid dispersion in a chaotic advection flow." International Journal of Multiphase Flow 35, no. 6 (June 2009): 485–97. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2009.02.019.

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Sherif Adham Mohamed. "Theoretical Drying Model of Water Vapor Pressure for Imbibed Porous Material with Sea Water subjected to Weather Conditions." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 87, no. 2 (September 26, 2021): 127–36. http://dx.doi.org/10.37934/arfmts.87.2.127136.

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The drying model of porous material has been studied and solved. The drying model solves the drying of porous material if the porous material is saturated or unsaturated with salt solution. Local thermodynamic equilibrium was not assumed in the mathematical model for describing the multi-phase flow in the unsaturated porous media using the energy and mass conservation equations to describe the heat and mass transfer during the drying. The vapor pressure inside porous material voids is built from the vapor mass transport through material thickness and from the void’s water content evaporation. The new equation in the model is water vapor pressure’s equation. The drying model included advection and capillary transport of the water in porous material pores, the gases transport by advection and diffusion and soluble salt transports by diffusion only. The environment of the boundary condition of the model is atmospheric condition in the day’s hours. The model consists of 5 equations for mass and heat transfer phenomenon. The model was solved by Matlab software. The case study of the model is concrete block.

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Sun, Yubiao, Amitesh S. Jayaraman, and Gregory S. Chirikjian. "Lie group solutions of advection-diffusion equations." Physics of Fluids 33, no. 4 (April 2021): 046604. http://dx.doi.org/10.1063/5.0048467.

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Espinosa Ramírez, A. C., and Oscar Velasco Fuentes. "Vortex polygons: Dynamics and associated particle advection." Physics of Fluids 33, no. 5 (May 2021): 057114. http://dx.doi.org/10.1063/5.0049841.

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Sukhovey, V. F., and T. Camara. "Thermal advection in the tropical Atlantic upper layer." Physical Oceanography 6, no. 6 (November 1995): 399–410. http://dx.doi.org/10.1007/bf02197465.

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Nahed, Jean, and Joseph Dgheim. "Estimation curvature in PLIC-VOF method for interface advection." Heat and Mass Transfer 56, no. 3 (September 11, 2019): 773–87. http://dx.doi.org/10.1007/s00231-019-02737-4.

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Ranjan, A., and P. A. Davidson. "Columnar heat transport via advection induced by inertial waves." International Journal of Heat and Fluid Flow 87 (February 2021): 108703. http://dx.doi.org/10.1016/j.ijheatfluidflow.2020.108703.

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Peerhossaini, H., C. Castelain, and Y. Le Guer. "Heat exchanger design based on chaotic advection." Experimental Thermal and Fluid Science 7, no. 4 (November 1993): 333–44. http://dx.doi.org/10.1016/0894-1777(93)90056-o.

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Jiménez-Robles, Alfonso Miguel, Stefano Lanzoni, and Miguel Ortega-SÃ¡nchez. "IMPLICATIONS OF PLUME DISCHARGE FOR TIDAL CHANNELS MORPHODYNAMICS: A COUPLED ONSHORE AND OFFSHORE SYSTEM." Coastal Engineering Proceedings, no. 35 (June 23, 2017): 12. http://dx.doi.org/10.9753/icce.v35.sediment.12.

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This contribution investigates the morphodynamic equilibrium of a funnel-shaped, well-mixed tidal channel taking into account the existing dynamical coupling between the tidal channel itself and the related offshore sediment-laden plume. We use a quasi two-dimensional numerical model that resolves the fully nonlinear unsteady shallow water, sediment bed load transport and suspended sediment advection-diffusion equations along with the Exner equation for the bathymetric changes. We close this model by including a dynamic boundary condition at the channel mouth that transfers the offshore plume sediment concentration to the channel dynamics. This model reveals that the offshore plume reduces the timescales to reach equilibrium of the channel and plays a crucial role on shaping it. At equilibrium, the non-plume influence case attains a quasi-linear profile of constant slope in the seaward part. However, the bottom profile in the case that includes the offshore plume tends to increase the concavity of the bottom profile, reducing the final channel mouth depth. Finally, numerical results suggest that the plume characteristics are altered as a consequence of tidal channel evolution.

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Zhao, Jiangming, Ziguang Chen, Javad Mehrmashhadi, and Florin Bobaru. "Construction of a peridynamic model for transient advection-diffusion problems." International Journal of Heat and Mass Transfer 126 (November 2018): 1253–66. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2018.06.075.

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Dutta, P., and R. Chevray. "Enhancement of mixing by chaotic advection with diffusion." Experimental Thermal and Fluid Science 11, no. 1 (July 1995): 1–12. http://dx.doi.org/10.1016/0894-1777(94)00098-s.

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Wooten, Brandi L., Koen Vandaele, Stephen R. Boona, and Joseph P. Heremans. "Combining Spin-Seebeck and Nernst Effects in Aligned MnBi/Bi Composites." Nanomaterials 10, no. 10 (October 21, 2020): 2083. http://dx.doi.org/10.3390/nano10102083.

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The spin-Seebeck effect (SSE) is an advective transport process traditionally studied in bilayers composed of a ferromagnet (FM) and a non-magnetic metal (NM) with strong spin-orbit coupling. In a temperature gradient, the flux of magnons in the FM transfers spin-angular momentum to electrons in the NM, which by the inverse spin-Hall effect generates an SSE voltage. In contrast, the Nernst effect is a bulk transport phenomenon in homogeneous NMs or FMs. These effects share the same geometry, and we show here that they can be added to each other in a new combination of FM/NM composites where synthesis via in-field annealing results in the FM material (MnBi) forming aligned needles inside an NM matrix with strong spin-orbit coupling (SOC) (Bi). Through examination of the materials’ microstructural, magnetic, and transport properties, we searched for signs of enhanced transverse thermopower facilitated by an SSE contribution from MnBi adding to the Nernst effect in Bi. Our results indicate that these two signals are additive in samples with lower MnBi concentrations, suggesting a new way forward in the study of SSE composite materials.

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Doglioli, Andrea M., Francesco Nencioli, Anne A. Petrenko, Gilles Rougier, Jean-Luc Fuda, and Nicolas Grima. "A Software Package and Hardware Tools for in situ Experiments in a Lagrangian Reference Frame." Journal of Atmospheric and Oceanic Technology 30, no. 8 (August 1, 2013): 1940–50. http://dx.doi.org/10.1175/jtech-d-12-00183.1.

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Abstract The Lagrangian Transport Experiment (LATEX) was developed to study the influence of coupled physical and biogeochemical dynamics at the meso- and submesoscales on the transfers of matter and heat between the coastal zone and the open ocean. One of the goals of the Latex10 field experiment, conducted during September 2010 in the Gulf of Lion (northwest Mediterranean), was to mark a dynamical mesoscale feature by releasing a passive tracer [sulfur hexafluoride (SF6)] together with an array of Lagrangian buoys. The goal was to release the tracer in an initial patch as homogeneous as possible in the horizontal, and to study its turbulent mixing and dispersion while minimizing the contribution due to advection. For that, it was necessary to continuously adjust the vessel route in order to remain as closely as possible in the Lagrangian reference frame moving with the investigated mesoscale structure. To accomplish this task, a methodology and software were developed, which are presented here. The software is equipped with a series of graphical and user-friendly accessories and the entire package for MATLAB can be freely downloaded (http://mio.pytheas.univ-amu.fr/~doglioli).

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Zakharchuk, E. A., and N. A. Tikhonova. "The influence of momentum advection on the Baltic Sea dynamics." Russian Meteorology and Hydrology 33, no. 8 (August 2008): 507–13. http://dx.doi.org/10.3103/s1068373908080050.

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Gershuni, G. Z., A. V. Shalimov, and V. M. Myznikov. "Plane-parallel advective binary mixture flow stability in a horizontal layer." International Journal of Heat and Mass Transfer 37, no. 15 (October 1994): 2327–42. http://dx.doi.org/10.1016/0017-9310(94)90374-3.

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Le, T. D., C. Moyne, and M. Sans. "Homogenized models of conduction-advection-radiation heat transfer in porous media." International Journal of Heat and Mass Transfer 194 (September 2022): 123056. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2022.123056.

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Reynolds, A. M. "Chaotic advection in the near-wake of a low-rise building." Fluid Dynamics Research 22, no. 6 (June 1998): 317–28. http://dx.doi.org/10.1016/s0169-5983(97)00047-6.

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Birikh, R. V., and T. N. Katanova. "Effect of high-frequency vibrations on the stability of advective flow." Fluid Dynamics 33, no. 1 (January 1998): 12–17. http://dx.doi.org/10.1007/bf02698155.

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Savva, Miles A. C., and Jacques Vanneste. "Scattering of internal tides by barotropic quasigeostrophic flows." Journal of Fluid Mechanics 856 (October 5, 2018): 504–30. http://dx.doi.org/10.1017/jfm.2018.694.

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Oceanic internal tides and other inertia–gravity waves propagate in an energetic turbulent flow whose length scales are similar to the wavelengths. Advection and refraction by this flow cause the scattering of the waves, redistributing their energy in wavevector space. As a result, initially plane waves radiated from a source such as a topographic ridge become spatially incoherent away from the source. To examine this process, we derive a kinetic equation which describes the statistics of the scattering under the assumptions that the flow is quasigeostrophic, barotropic and well represented by a stationary homogeneous random field. Energy transfers are quantified by computing a scattering cross-section and shown to be restricted to waves with the same frequency and identical vertical structure, hence the same horizontal wavelength. For isotropic flows, scattering leads to an isotropic wave field. We estimate the characteristic time and length scales of this isotropisation, and study their dependence on parameters including the energy spectrum of the flow. Simulations of internal tides generated by a planar wavemaker carried out for the linearised shallow-water model confirm the pertinence of these scales. A comparison with the numerical solution of the kinetic equation demonstrates the validity of the latter and illustrates how the interplay between wave scattering and transport shapes the wave statistics.

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Gomes-Fernandes, R., B. Ganapathisubramani, and J. C. Vassilicos. "The energy cascade in near-field non-homogeneous non-isotropic turbulence." Journal of Fluid Mechanics 771 (April 23, 2015): 676–705. http://dx.doi.org/10.1017/jfm.2015.201.

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We perform particle image velocimetry (PIV) measurements of various terms of the non-homogeneous Kármán–Howarth–Monin equation in the most inhomogeneous and anisotropic region of grid-generated turbulence, the production region which lies between the grid and the peak of turbulence intensity. We use a well-documented fractal grid which is known to magnify the streamwise extent of the production region and abate its turbulence activity. On the centreline around the centre of that region the two-point advection and transport terms are dominant and the production is significant too. It is therefore impossible to apply usual Kolmogorov arguments based on the Kármán–Howarth–Monin equation and resulting dimensional considerations to deduce interscale flux and spectral properties. The interscale energy transfers at this location turn out to be highly anisotropic and consist of a combined forward and inverse cascade in different directions which, when averaged over directions, gives an interscale energy flux that is negative (hence forward cascade on average) and not too far from linear in $r$, the modulus of the separation vector $\boldsymbol{r}$ between two points. The energy spectrum of the streamwise fluctuating component exhibits a well-defined $-5/3$ power law over one decade, even though the streamwise direction is at a small angle to the inverse cascading direction.

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Babaee, H., and T. P. Sapsis. "A minimization principle for the description of modes associated with finite-time instabilities." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2186 (February 2016): 20150779. http://dx.doi.org/10.1098/rspa.2015.0779.

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We introduce a minimization formulation for the determination of a finite-dimensional, time-dependent, orthonormal basis that captures directions of the phase space associated with transient instabilities. While these instabilities have finite lifetime, they can play a crucial role either by altering the system dynamics through the activation of other instabilities or by creating sudden nonlinear energy transfers that lead to extreme responses. However, their essentially transient character makes their description a particularly challenging task. We develop a minimization framework that focuses on the optimal approximation of the system dynamics in the neighbourhood of the system state. This minimization formulation results in differential equations that evolve a time-dependent basis so that it optimally approximates the most unstable directions. We demonstrate the capability of the method for two families of problems: (i) linear systems, including the advection–diffusion operator in a strongly non-normal regime as well as the Orr–Sommerfeld/Squire operator, and (ii) nonlinear problems, including a low-dimensional system with transient instabilities and the vertical jet in cross-flow. We demonstrate that the time-dependent subspace captures the strongly transient non-normal energy growth (in the short-time regime), while for longer times the modes capture the expected asymptotic behaviour.

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Jupsin, H., E. Praet, and J. L. Vasel. "Dynamic mathematical model of high rate algal ponds (HRAP)." Water Science and Technology 48, no. 2 (July 1, 2003): 197–204. http://dx.doi.org/10.2166/wst.2003.0120.

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This article presents a mathematical model to describe High-Rate Algal Ponds (HRAPs). The hydrodynamic behavior of the reactor is described as completely mixed tanks in series with recirculation. The hydrodynamic pattern is combined with a subset of River Water Quality Model 1 (RWQM1), including the main processes in liquid phase. Our aim is to develop models for WSPs and aerated lagoons, too, but we focused on HRAPs first for several reasons:• Sediments are usually less abundant in HRAP and can be neglected• Stratification is not observed and state variables are constant in a reactor cross section• Due to the system's geometry, the reactor is quite similar to a plugflow type reactor with recirculation, with a simple advection term. The model is based on mass balances and includes the following processes:Phytoplankton growth with NO3-, NO2- and death• Aerobic growth of heterotrophs with NO3-, NH4+ and respiration• Anoxic growth of heterotrophs with NO3-, NO2- and anoxic respiration• Growth of nitrifiers (two stages) and respiration. The differences with regard to RWQM1 are that we included a limiting term associated with inorganic carbon on the growth rate of algae and nitrifiers, gas transfers are taken into account by the familiar Adeney equation, and a subroutine calculates light intensity at the water surface. This article presents our first simulations.

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Hekmatzadeh, Ali Akbar, Ali Adel, Farshad Zarei, and Ali Torabi Haghighi. "Probabilistic simulation of advection-reaction-dispersion equation using random lattice Boltzmann method." International Journal of Heat and Mass Transfer 144 (December 2019): 118647. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2019.118647.

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Ryzhov, E., K. Koshel, and D. Stepanov. "Background current concept and chaotic advection in an oceanic vortex flow." Theoretical and Computational Fluid Dynamics 24, no. 1-4 (October 27, 2009): 59–64. http://dx.doi.org/10.1007/s00162-009-0170-1.

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Nakamichi, Takeshi, and Toshitsugu Moroizumi. "Applicability of three complementary relationship models for estimating actual evapotranspiration in urban area." Journal of Hydrology and Hydromechanics 63, no. 2 (June 1, 2015): 117–23. http://dx.doi.org/10.1515/johh-2015-0011.

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Abstract The characteristics of evapotranspiration estimated by the complementary relationship actual evapotranspiration (CRAE), the advection-aridity (AA), and the modified advection-aridity (MAA) models were investigated in six pairs of rural and urban areas of Japan in order to evaluate the applicability of the three models the urban area. The main results are as follows: 1) The MAA model could apply to estimating the actual evapotranspiration in the urban area. 2) The actual evapotranspirations estimated by the three models were much less in the urban area than in the rural. 3) The difference among the estimated values of evapotranspiration in the urban areas was significant, depending on each model, while the difference among the values in the rural areas was relatively small. 4) All three models underestimated the actual evapotranspiration in the urban areas from humid surfaces where water and green spaces exist. 5) Each model could take the effect of urbanization into account.

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Koshel, K. V., M. A. Sokolovskiy, and P. A. Davies. "Chaotic advection and nonlinear resonances in an oceanic flow above submerged obstacle." Fluid Dynamics Research 40, no. 10 (October 2008): 695–736. http://dx.doi.org/10.1016/j.fluiddyn.2008.03.001.

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Tohidi, A., S. M. Hosseinalipour, P. Taheri, N. M. Nouri, and A. S. Mujumdar. "Chaotic advection induced heat transfer enhancement in a chevron-type plate heat exchanger." Heat and Mass Transfer 49, no. 11 (November 2013): 1535–48. http://dx.doi.org/10.1007/s00231-013-1180-5.

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45

Aldor, Abbas, Yann Moguen, Kamal El Omari, Charbel Habchi, Pierre-Henri Cocquet, and Yves Le Guer. "Heat transfer enhancement by chaotic advection in a novel sine-helical channel geometry." International Journal of Heat and Mass Transfer 193 (September 2022): 122870. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2022.122870.

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Lejeune, Yves, Ludovic Bouilloud, Pierre Etchevers, Patrick Wagnon, Pierre Chevallier, Jean-Emmanuel Sicart, Eric Martin, and Florence Habets. "Melting of Snow Cover in a Tropical Mountain Environment in Bolivia: Processes and Modeling." Journal of Hydrometeorology 8, no. 4 (August 1, 2007): 922–37. http://dx.doi.org/10.1175/jhm590.1.

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Abstract To determine the physical processes involved in the melting and disappearance of transient snow cover in nonglacierized tropical areas, the CROCUS snow model, interactions between Soil–Biosphere–Atmosphere (ISBA) land surface model, and coupled ISBA/CROCUS model have been applied to a full set of meteorological data recorded at 4795 m MSL on a moraine area in Bolivia (16°17′S, 68°32′W) between 14 May 2002 and 15 July 2003. The models have been adapted to tropical conditions, in particular the high level of incident solar radiation throughout the year. As long as a suitable function is included to represent the mosaic partitioning of the surface between snow cover and bare ground and local fresh snow grain type (as graupel) is adapted, the ISBA and ISBA/CROCUS models can accurately simulate snow behavior over nonglacierized natural surfaces in the Tropics. Incident solar radiation is responsible for efficient melting of the snow surface (favored by fresh snow albedo values usually not exceeding 0.8) and also for the energy stored in snow-free areas (albedo = 0.18) and transferred horizontally to adjacent snow patches. These horizontal energy transfers (by conduction within the upper soil layers and by turbulent advection) explain most of the snowmelt and prevent the snow cover from lasting more than a few days during the wet season in this high-altitude tropical environment.

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Lyubimova, T. P., and D. A. Nikitin. "Stability of the advective flow in a horizontal rectangular channel with adiabatic boundaries." Fluid Dynamics 46, no. 2 (April 2011): 240–49. http://dx.doi.org/10.1134/s0015462811020062.

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Schwarz, E. G. "Plane-parallel advective flow in a horizontal incompressible fluid layer with rigid boundaries." Fluid Dynamics 49, no. 4 (July 2014): 438–42. http://dx.doi.org/10.1134/s0015462814040036.

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Trujillo, Mario F., and Alex E. Parkhill. "A local lagrangian analysis of passive particle advection in a gas flow field." International Journal of Multiphase Flow 37, no. 9 (November 2011): 1201–8. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2011.06.003.

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Etzold, M. A., J. R. Landel, and Stuart B. Dalziel. "Three-dimensional advective–diffusive boundary layers in open channels with parallel and inclined walls." International Journal of Heat and Mass Transfer 153 (June 2020): 119504. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2020.119504.

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Journal articles on the topic 'Transferts advectifs'

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