Relevant bibliographies by topics / High Prandtl

Academic literature on the topic 'High Prandtl'

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Published: 11 March 2023

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Journal articles on the topic "High Prandtl"

KAMINSKI, EDOUARD, and CLAUDE JAUPART. "Laminar starting plumes in high-Prandtl-number fluids." Journal of Fluid Mechanics 478 (March 10, 2003): 287–98. http://dx.doi.org/10.1017/s0022112002003233.

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Experimental studies of laminar axisymmetric starting plumes are performed to investigate the dependence of the flow on the Prandtl number, focusing on large Prandtl numbers. Thermal plumes are generated by a small electric heater in a glass tank filled with viscous oils. Prandtl numbers in the range of 7–104 were investigated. Experimental conditions are such that viscosity variations due to temperature differences are negligible. Plumes ascend in two different regimes as a function of distance to source. At short distances, the plumes accelerate owing to the development of the viscous boundary layer. At distances larger than about five times the heater size, the ascent velocity is constant and increases as a function of the Prandtl number, as predicted by theory for steady plumes. This velocity is, within experimental error, proportional to the steady plume centreline velocity.

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Jin, Y. Y., and C. F. Chen. "Instability of Convection and Heat Transfer of High Prandtl Number Fluids in a Vertical Slot." Journal of Heat Transfer 118, no. 2 (May 1, 1996): 359–65. http://dx.doi.org/10.1115/1.2825852.

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The stability of convective motion of high-Prandtl-number fluids, generated by a lateral temperature difference across a vertical slot with aspect ratio 15, is studied numerically. The Prandtl number range studied is from 50 to 2000. The nonlinear governing equations are solved by a finite difference method. The predicted flow patterns and critical values are in good agreement with the recent experimental results of Wakitani (1994). It is found that the vorticity distribution along the vertical centerline of the slot is a very sensitive indicator of the onset of multicellular flow. The critical Grashof number varies almost inversely with the Prandtl number; consequently, the critical Rayleigh number is essentially independent of the Prandtl number. Heat transfer results show good agreement with the experimentally correlated values, and they are independent of the Prandtl numbers and the flow patterns.

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Busse, F. H., M. A. Zaks, and O. Brausch. "Centrifugally driven thermal convection at high Prandtl numbers." Physica D: Nonlinear Phenomena 184, no. 1-4 (October 2003): 3–20. http://dx.doi.org/10.1016/s0167-2789(03)00210-0.

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Liang, Ru Quan, Shuo Yang, Fu Sheng Yan, Jun Hong Ji, and Ji Cheng He. "Numerical Study on High Prandtl Number Liquid Bridge." Advanced Materials Research 712-715 (June 2013): 1630–33. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.1630.

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The overall numerical analysis of liquid bridge for high Pr number fluid and flow field of ambient air under the zero-gravity environment was carried out in the present paper. The paper used level set method of mass conservation to capture two phase interfaces. Not only the free surface deformation was considered, but also the effect of ambient gas was taken into account. Simultaneously, results of stream function in liquid bridge and ambient gas-phase were given.

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Kolyshkin, A., and Rémi Vaillancourt. "Stability of internally generated thermal convection in a tall vertical annulus." Canadian Journal of Physics 69, no. 6 (June 1, 1991): 743–48. http://dx.doi.org/10.1139/p91-124.

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The stabilityof a convective fluid motion generated by internal heat sources in a tall vertical annulus is investigated by means of a mathematical model in the cases of both axisymmetric and asymmetric disturbances. The critical Grasshof numbers are computed for several values of the Prandtl number and different sizes of the gap between the cylinders. It is found that, for low Prandtl numbers and large gaps, asymmetric disturbances lead to instability while, in the case of small gaps, instability is associated with axisymmetric disturbances. In both cases, the critical Grasshof number increases as the gap decreases. For high values of the Prandtl number, instability occurs in the form of thermal running waves. The critical Grasshof numbers decrease as the Prandtl number grows. The neutral stability curve has one or two closed loops for sufficiently high Prandtl numbers. It is found that for high Prandtl numbers instability is associated with axisymmetric perturbations at least in the interval 0.05 < R < 1, where R is the ratio of the inner to the outer radii.

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Gargano, F., M. Sammartino, V. Sciacca, and K. W. Cassel. "Analysis of complex singularities in high-Reynolds-number Navier–Stokes solutions." Journal of Fluid Mechanics 747 (April 17, 2014): 381–421. http://dx.doi.org/10.1017/jfm.2014.153.

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AbstractNumerical solutions of the laminar Prandtl boundary-layer and Navier–Stokes equations are considered for the case of the two-dimensional uniform flow past an impulsively-started circular cylinder. The various viscous–inviscid interactions that occur during the unsteady separation process are investigated by applying complex singularity analysis to the wall shear and streamwise velocity component of the two solutions. This is carried out using two different methodologies, namely a singularity-tracking method and the Padé approximation. It is shown how the van Dommelen and Shen singularity that occurs in solutions of the Prandtl boundary-layer equations evolves in the complex plane before leading to a separation singularity in finite time. Navier–Stokes solutions, computed at different Reynolds numbers in the range$10^3 \leq Re \leq 10^5$, are characterized by the presence of various complex singularities that can be related to different physical interactions acting over multiple spatial scales. The first interaction developing in the separation process is large-scale interaction that is visible for all the Reynolds numbers considered, and it signals the first relevant differences between the Prandtl and Navier–Stokes solutions. For$Re\geq O(10^4)$, a small-scale interaction follows the large-scale interaction. The onset of these interactions is related to the characteristic changes of the streamwise pressure gradient on the circular cylinder. Even if these interactions physically differ from that prescribed by the Prandtl solution, and they set a possible limit on the comparison of Prandtl solutions with Navier–Stokes solutions, it is shown how the asymptotic validity of boundary-layer theory is strongly supported by the results that have been obtained through the complex singularity analysis.

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Chan, C. L., M. M. Chen, and J. Mazumder. "Asymptotic Solution for Thermocapillary Flow at High and Low Prandtl Numbers Due to Concentrated Surface Heating." Journal of Heat Transfer 110, no. 1 (February 1, 1988): 140–46. http://dx.doi.org/10.1115/1.3250444.

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Thermocapillary convection due to nonuniform surface heating is the dominant form of fluid motion in many materials processing operations. The velocity and temperature distributions for the region adjacent to the area of peak surface heating are analyzed for the limiting cases of large and small Prandtl numbers. For a melt pool whose depth and width are large relative to the thermal and viscous boundary layers, it is shown that the most important parameter is the curvature (i.e., ∇2q) of the surface heat flux distribution. The solutions of the temperature and stream functions are presented, some of which are in closed form. Simple, explicit expressions for the velocity and maximum temperature are presented. These results are found to be quite accurate for realistic Prandtl number ranges, in comparison with exact solutions for finite Prandtl numbers. Besides being more concise than exact results, the asymptotic results also display the Prandtl number dependence more clearly in the respective ranges.

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Or, A. C. "Chaotic transitions of convection rolls in a rapidly rotating annulus." Journal of Fluid Mechanics 261 (February 25, 1994): 1–19. http://dx.doi.org/10.1017/s0022112094000224.

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Drifting convection rolls in a rapidly rotating cylindrical annulus with conical endwalls exhibit different transitional modes to chaotic flows at different Prandtl numbers. Three transition sequences for Prandtl numbers 0.3, 1.0 and 7.0 are studied for a moderately large Coriolis parameter and a wavenumber near the critical value using an initial-value code. As the Rayleigh number increases, each transition sequence first leads to a vacillating flow, and then to an aperiodic flow, the route of which is Prandtl-number dependent. From the low Prandtl number to the high Prandtl number, the transitions take different routes of torus folding, period doubling, and mode-locking intermittency.

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Mkhinini, Nadia, Thomas Dubos, and Philippe Drobinski. "Secondary instability of the stably stratified Ekman layer." Journal of Fluid Mechanics 728 (July 1, 2013): 29–57. http://dx.doi.org/10.1017/jfm.2013.250.

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AbstractThe Ekman flow, an exact solution of the Boussinesq equations with rotation, is a prototype flow for both atmospheric and oceanic boundary layers. The effect of stratification on the finite-amplitude longitudinal rolls developing in the Ekman flow and their three-dimensional stability is studied by means of linearized and nonlinear numerical simulations. Similarities and differences with respect to billows developing in the Kelvin–Helmholtz (KH) unidirectional stratified shear flow are discussed. Prandtl number effects are investigated as well as the role played by the buoyant-convective instability. For low Prandtl number, the amplitude of the saturated rolls vanishes at the critical bulk Richardson number, while at high Prandtl number, finite-amplitude rolls are found. The Prandtl number also affects how the growth rate of the secondary instability evolves as the Richardson number is increased. For low Prandtl number, the growth rate decreases as the Richardson number increases while it remains significant for large Prandtl number over the range of stratification studied. This behaviour is likely a result of the differing amplitudes of the roll vortices. Furthermore, the most unstable wave vector is much lower than for the secondary instability of KH billows. Examination of the energetics of the secondary instability shows that buoyant-convective instability is present locally at high Reynolds and Prandtl numbers but plays an overall minor role despite the presence in the base flow of statically unstable regions characterized by a high Richardson number.

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Orvedahl, Ryan J., Michael A. Calkins, Nicholas A. Featherstone, and Bradley W. Hindman. "Prandtl-number Effects in High-Rayleigh-number Spherical Convection." Astrophysical Journal 856, no. 1 (March 20, 2018): 13. http://dx.doi.org/10.3847/1538-4357/aaaeb5.

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Dissertations / Theses on the topic "High Prandtl"

Silano, Gabriella. "Numerical simulations of thermal convection at high Prandtl numbers." Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3211.

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2007/2008
In this thesis we present the results of an extensive campaign of direct numerical simulations of Rayleigh-B\'enard convection at high Prandtl numbers ($10^{-1}\leq Pr \leq 10^4$) and moderate Rayleigh numbers ($10^{5}\leq Pr \leq 10^9$). The computational domain is a cylindrical cell of aspect-ratio (diameter over cell height) $\Gamma=1/2$, with the no-slip condition imposed to the boundaries. By scaling the results, we find a $1/\sqrt{Pr}$ correction to apply to the free-fall velocity, obtaining a more appropriate representation of the large scale velocity at high $Pr$. We investigate the Nusselt and the Reynolds number dependence on $Ra$ and $Pr$, comparing the results to previous numerical and experimental work. At high $Pr$ the scaling behavior of the Nusselt number with respect to $Ra$ is generally consistent with the power-law exponent $0.309$. The Nusselt number is independent of $Pr$, even at the highest $Ra$ simulated. The Reynolds number scales as $Re\sim \sqrt{Ra}/Pr$, neglecting logarithmic corrections. We analyze the global and local features of viscous and thermal boundary layers and their scaling behavior with respect to Rayleigh and Prandtl numbers, and with respect to Reynolds and Peclet numbers. We find that the flow approaches a saturation regime when Reynolds number decreases below the critical value $Re_s\simeq 40$. The thermal boundary layer thickness turns out to increase slightly even when the Peclet number increases. We explain this behavior as a combined effect of the Peclet number and the viscous boundary layer influences. The range of $Ra$ and $Pr$ simulated contains steady, periodic and turbulent solutions. A rough estimate of the transition from steady to unsteady flow is obtained by monitoring the time-evolution of the system until it reaches stationary solutions ($Ra_U\simeq 7.5 \times 10^6$ at $Pr=10^3$). We find multiple solutions as long-term phenomena at $Ra=10^8$ and $Pr=10^3$ which, however, do not result in significantly different Nusselt number. One of these multiple solutions, even if stable for a long time interval, shows a break in the mid-plane symmetry of the temperature profile. The result is similar to that of some non-Boussinesq effects. We analyze the flow structures through the transitional phases by direct visualizations of the temperature and velocity fields. We also describe how the behavior of the flow structures changes for increasing $Pr$. A wide variety of large-scale circulations and plumes structures are found. The single-roll circulation is characteristic only of the steady and periodic solutions. For other solutions, at lower $Pr$, the mean flow generally consists of two opposite toroidal structures; at higher $Pr$, the flow is organized in multi-cell structures extending mostly in the vertical direction. At high $Pr$, plumes detach from sheet-like structures. The different large-scale-structure signatures are generally reflected in the data trends with respect to $Ra$, but not in those with respect to $Pr$. In particular, the Nusselt number is independent of $Pr$, even when the flow structures appear strongly different varying $Pr$. In order to assess the reliability of the data-set we perform a systematic analysis of the error affecting the data. Refinement grid analysis is extensively applied.
---------------------------------------------------------------------------------------- In questa tesi presentiamo i risultati di un'estensiva campagna di simulazioni numeriche dirette della convezione di Rayleigh-B\'enard ad alti numeri di Prandtl ($10^{-1}\leq Pr \leq 10^4$) e moderati numeri di Rayleigh ($10^{5}\leq Pr \leq 10^9$). Il dominio computazionale \`e una cella cilindrica di allungamento (diametro su altezza cella) $\Gamma=1/2$, con condizioni di non-slittamento ai contorni. Scalando i risultati, troviamo una correzione di $1/\sqrt{Pr}$ da applicare alla velocit\`a di caduta libera, ottenendo una rappresentazione pi\`u appropriata della velocit\`a di larga scala ad elevati $Pr$. Investighiamo la dipendenza del numero di Nusselt e del numero di Reynolds da $Ra$ e $Pr$, comparando i risultati con precedenti lavori numerici e sperimentali. Ad elevati $Pr$ il comportamento di scala del numero di Nusselt rispetto a $Ra$ \`e generalmente compatibile con l'esponente di legge di potenza $0.309$. Il numero di Nusselt \`e indipendente da $Pr$, anche per il pi\`u alto $Ra$ simulato. Il numero di Reynolds scala come $Re\sim \sqrt{Ra}/Pr$, a meno di correzioni logaritmiche. Analizziamo le caratteristiche locali e globali degli strati limite viscosi e termici, ed il loro comportamento di scala rispetto ai numeri Rayleigh e Prandtl, e rispetto ai numeri Reynolds e Peclet. Troviamo che il flusso approccia un regime di saturazione quando il numero di Reynolds scende sotto il valore critico $Re_s\simeq 40$. Lo spessore dello strato limite termico comincia a crescere leggermente anche quando in numero di Peclet aumenta. Spieghiamo questo comportamento come un effetto combinato delle influenze del numero di Peclet e dello strato limite viscoso. L'intervallo di $Ra$ e $Pr$ simulato contiene soluzioni stazionarie, periodiche e turbolente. Una stima approssimata della transizione da flusso stazionario a non stazionario \`e ottenuta monitorando l'evoluzione temporale del sistema fino al raggiungimento di soluzioni stazionarie o statisticamente stazionarie ($Ra_U\simeq 7.5 \times 10^6$ a $Pr=10^3$). Troviamo soluzioni multiple come fenomeni di lungo termine a $Ra=10^8$ e $Pr=10^3$ che, comunque, non comportano differenze significative nel numero di Nusselt. Una di queste soluzioni multiple, anche se stabile per un lungo intervallo di tempo, mostra una rottura della simmetria del profilo di temperatura rispetto al piano mediano. Il risultato \`e simile a quello di alcuni effetti di non-Boussinesq. Analizziamo le strutture del flusso nelle fasi di transizione tramite visualizzazioni dirette dei campi di velocit\`a e temperatura. Descriviamo inoltre come il comportamento delle strutture del flusso cambia al crescere di $Pr$. Un'ampia variet\`a di circolazioni di larga scala e strutture a pennacchio vengono trovate. La circolazione a singolo anello \`e caratteristica solo delle soluzioni stazionarie e periodiche. Per le altre soluzioni, a $Pr$ pi\`u bassi, il flusso medio \`e generalmente composto da due strutture toroidali opposte; a $Pr$ pi\`u alti, il flusso \`e organizzato in strutture multi-cellulari che si estendono maggiormente in direzione verticale. Ad alti $Pr$, pennacchi si staccano da strutture simili a fogli. Le impronte delle differenti strutture di larga scala si riflettono generalmente nell'andamento dei dati rispetto a $Ra$, ma non rispetto a $Pr$. In particolare, il numero di Nusselt \`e indipendente da $Pr$, anche quando le strutture del flusso appaiono molto differenti al variare di $Pr$. Per stabilire l'affidabilit\`a dell'insieme dei dati, effettuiamo un'analisi sistematica degli errori a cui i dati sono soggetti. L'analisi di raffinamento della griglia \`e largamente applicata.
XXI Ciclo
1976

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Pickles, K. "Velocity measurements in a thermally convecting high prandtl number fluid." Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354406.

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Arasanipalai, Sriram Sharan. "Two-equation model computations of high-speed (ma=2.25, 7.2), turbulent boundary layers." Thesis, [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3186.

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Wang, Aihua. "Effects of free surface heat transfer and shape on thermocapillary flow of high Prandtl number fluids." online version, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1094225212.

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Younis, Taha Elamin Obai. "Numerical and experimental study of transient laminar natural convection of high prandtl number fluids in a cubical cavity." Doctoral thesis, Universitat Rovira i Virgili, 2009. http://hdl.handle.net/10803/8496.

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NUMERICAL AND EXPERIMENTAL STUDY OF TRANSIENT LAMINAR NATURAL CONVECTION OF HIGH PRANDTL NUMBER FLUIDS IN A CUBICAL CAVITY
Obai Younis Taha Elamin

La convección natural en espacios cerrados, se encuentra ampliamente en sistemas naturales e industriales. El objetivo general de este trabajo es desarrollar y validar una herramienta de simulación capaz de predecir las tasas de enfriamiento de aceite en un tanque. Esta herramienta ha de tener en cuenta la variación de la viscosidad del aceite para dar información detallada de las tasas de enfriamiento del aceite bajo diferentes condiciones de contorno térmicas realisticas.
En primer lugar, la influencia de diferentes condiciones de contorno térmicas en las paredes, la variación de la viscosidad y la conductividad de la pared en la convección natural del flujo laminar transitorio en una cavidad cúbica con seis paredes térmicamente activo están analizadas.
Para analizar el efecto individual de las paredes laterales de la cavidad en el proceso de enfriamiento, la segunda parte de este estudio considera que, tanto numéricamente como experimentalmente, la transición de la convección natural laminar en una cavidad cúbica con dos paredes opuestas frías y verticales.
Nuevas relaciones de escala que tengan en cuenta la variación de la viscosidad con la temperatura, no publicadas anteriormente en la literatura, se derivan de las velocidades de la capa límite, por el tiempo necesario para la capa límite para alcanzar el estado estacionario y para la velocidad y el espesor de las intrusiones horizontales.
NUMERICAL AND EXPERIMENTAL STUDY OF TRANSIENT LAMINAR NATURAL CONVECTION OF HIGH PRANDTL NUMBER FLUIDS IN A CUBICAL CAVITY
Obai Younis Taha Elamin

Free convection in enclosed spaces is found widely in natural and industrial systems. The general objective of this work is to develop and validate a simulation tool able to predict the cooling rates of oil in a tank. This tool has to take into account the variation of the oil viscosity to give detailed information of the cooling rates of the oil under different realistic thermal boundary conditions.
First, the influence of different thermal wall boundary conditions, the variation of the viscosity and the wall conductivity on the transient laminar natural convection flow in a cubical cavity with the six walls thermally active is studied numerically.
To analyze the individual effect of the side walls of the cavity on the cooling process, the second part of this study considers, numerically and experimentally, the transient laminar natural convection in a cubical cavity with two cold opposite vertical walls. The shadowgraph technique is employed to visualize the development of the transient convective flow. New scaling relations that take into account the viscosity variation with temperature, not reported previously in the literature, are derived for the boundary layer velocities, for the time needed for the boundary layer to reach the steady state and for the velocity and thickness of the horizontal intrusions.

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Munday, David. "Flow and Acoustics of Jets from Practical Nozzles for High-Performance Military Aircraft." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289842789.

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Best, Sampson Jill Nicole. "A High-fat Meal Alters Post-prandial mRNA Expression of SIRT1, SIRT4, and SIRT6." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822825/.

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Sirtuins (SIRT) regulate the transcription of various genes involved in the development of diet-induced obesity and chronic disease; however, it is unknown how they change acutely following a high-fat meal. The purpose of this study was to determine the effect of a high-fat meal (65% kcals/d; 85% fat recommendation), on SIRT1-7 mRNA expression in blood leukocytes at 1, 3, and 5-h post-prandial. Men and women (N=24) reported to the lab following an overnight fast (>12H). Total RNA was isolated and reverse transcribed prior to using a Taqman qPCR technique with 18S rRNA as a normalizer to determine SIRT1-7 mRNA expression. An additional aliquot of serum was used to measure triglycerides. Data was analyzed using a RM ANOVA with P<0.05. Triglycerides (P<0.001; 124%) peaked at 3-h. SIRT 1 (P=0.004; 70%), and SIRT 6 (P=0.017; 53%) decreased expression at 3-h. SIRT4 (P=0.024) peaked at 5H relative to baseline (70%) and 3-h (68%). To our knowledge, this is the first study to report that consumption of a high-fat meal transiently alters SIRT mRNA expression consistent in a pattern that mirrors changes in serum triglycerides. Decrease in expression of SIRT1 and SIRT6 combined with an increased SIRT4 would be consistent with an increase in metabolic disease risk if maintained on a chronic basis.

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Quintanilha, Bruna Jardim. "Efeito de uma refeição hiperlipídica no período pós-prandial sobre a expressão de microRNA em mulheres saudáveis." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/6/6138/tde-16042018-175847/.

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Introdução - Evidências mostram que a ingestão de uma refeição hipercalórica, rica em lipídios e açúcares, provoca elevação da concentração plasmática de glicose e de triacilgliceróis (TG), bem como de lipopolissacarídeos (LPS) no período pós-prandial. Sugere-se que essa condição esteja envolvida na gênese da inflamação subclínica, caracterizada pelo aumento da concentração de biomarcadores pró-inflamatórios na circulação sanguínea, como o fator de necrose tumoral (TNF)-α, interleucina (IL)-1β, IL- 6 e as moléculas de adesão intracelular solúvel (sICAM)-1 e vascular solúvel (sVCAM)- 1, o que contribui para o aumento do risco para doenças cardiovasculares. Estudos recentes sugerem que os microRNA (miRNA) atuam como biomarcadores inflamatórios e a análise da sua expressão no período pós-prandial pode contribuir para a redução do risco de doenças cardiovasculares. Objetivo - Investigar o efeito de uma refeição hiperlipídica, rica em ácidos graxos saturados, sobre a expressão de microRNA e a concentração de LPS no plasma no período pós-prandial em mulheres saudáveis. Métodos - Realizou-se um estudo de intervenção no qual foi oferecido uma refeição matinal com alto teor de lipídios, principalmente, de ácidos graxos saturados, mais 500 mL de água, realizando-se coletas de sangue no período basal e 1, 3 e 5 horas após a ingestão da refeição hiperlipídica. A população do estudo foi composta por mulheres saudáveis (n = 11), com idade entre 20 e 40 anos, e IMC de 18,5 a 25 kg/m². Foram avaliadas as concentrações plasmáticas de glicose, insulina, perfil lipídico e de ácidos graxos, citocinas, moléculas de adesão, MCP-1 e LPS. Analisou-se pelo ensaio de PCR em tempo real, um perfil de expressão de 752 miRNA plasmáticos humanos. Essas análises foram realizadas em todos os tempos da coleta de sangue. Resultados - Houve aumento significativo das concentrações plasmáticas de LPS e TG nos tempos 1, 3 e 5 horas em relação ao período basal. As concentrações plasmáticas de insulina elevaram-se de forma significativa após 1 e 3 horas em comparação ao período basal, e reduziu após 5 h se comparado ao tempo 1 h. Os ácidos graxos saturados plasmáticos mirístico e palmítico aumentaram após o consumo da refeição. Houve aumento das concentrações plasmáticas de TNF-α após 5h se comparado ao basal e ao tempo 1 h. E houve aumento da concentração de sVCAM-1 após 5 h vs o basal. Em relação aos miRNA, 45 miRNA tiveram suas concentrações alteradas se comparadas entre todos os tempos, destes 33 miRNA vs o basal. Conclusões - O aumento de TG e insulina após a refeição hiperlipídica pode contribuir para explicar a participação da dieta no desenvolvimento de um quadro inflamatório, promovido, também, por um quadro de endotoxemia pós-prandial. Junto a isso, os miRNA podem exercer papel importante na regulação deste quadro. Uma refeição hiperlipídica, com elevado teor de ácidos graxos saturados, ocasiona um quadro de endotoxemia metabólica e altera a expressão de microRNA plasmáticos envolvidos na regulação do processo inflamatório no período pós-prandial.
Introduction Evidence shows that a high caloric meal, rich in lipids and carbohydrates, increase glucose and triacyclglycerols (TG) concentrations, furthermore in lipopolysaccharides (LPS) in the postprandial period. This condition is involved with subclinic inflammation genesis, characterized by increased concentration of inflammatory biomarkers in blood circulation, like tumor necrose fator (TNF)-α, interleukin (IL)-1β, IL-6 and soluble intracellular adhesion molecule (sICAM)-1 and soluble vascular (sVCAM)-1, what contributes to rise cardiovascular disease risk. Recent studies indicate that microRNAs (miRNA) act as inflammatory biomarkers and analysis of their expression in the postprandial state could contribute to reduction of cardiovascular disease risk. Objective This study investigates the high-fat high-saturated meal effect above miRNA expression and LPS concentration at the postprandial period in healthy women. Methods An interventional study was carried out in which a breakfast with a high lipid content, mainly of saturated fatty acids, plus 500 mL of water was offered. Blood samples were collected at baseline and 1, 3 and 5 hours after ingestion of the high-fat meal. The study population consisted of healthy women (n = 11), aged between 20 and 40 years, and BMI of 18.5 to 25 kg / m². Plasma concentrations of glucose, insulin, lipid profile and fatty acids, cytokines, adhesion molecules, MCP-1 and LPS were evaluated. An expression profile of 752 human plasma miRNA was analyzed by the real-time PCR assay. These analyzes were performed at all times of blood collection. Results - There was a significant increase in the plasma concentrations of LPS and TG at times 1, 3, 5 hours in relation to the baseline. Plasma insulin concentrations increased significantly after 1 and 3 hours compared to baseline, and decreased after 5 h compared to 1 h. Myristic and palmitic saturated fatty acids increased after consumption of the meal. There was an increase in plasma concentrations of TNF-α after 5 hours compared to the baseline and at 1 h. And there was an increase in sVCAM-1 concentration after 5 hours vs baseline. Regarding the miRNA, 45 miRNA had their concentrations altered when compared among all the times, of these 33 miRNA vs the baseline. Conclusions - The increase of TG and insulin after the high-fat meal may contribute to explain diet participation in the development of an inflammatory condition, also promoted by postprandial endotoxemia. In addition, microRNAs may play a key role in the regulation of this condition. High-fat high-saturated meal generates a metabolic endotoxemia state and changes plasma microRNAs expression which are involved in regulation to inflammatory process in the postprandial period.

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"Experimental investigation of high prandtl number turbulent convection." 2000. http://library.cuhk.edu.hk/record=b5895803.

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Lam Siu = 高普朗特數湍流對流的實驗硏究 / 林霄.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.
Includes bibliographical references (leaves 97-100).
Text in English; abstracts in English and Chinese.
Lam Siu = Gao pu lang te shu tuan liu dui liu de shi yan yan jiu / Lin Xiao.
Abstract (in English) --- p.i
Abstract (in Chinese) --- p.ii
Acknowledgements --- p.iii
Table of Contents --- p.iv
List of Figures --- p.vi
List of Tables --- p.ix
Chapters
Chapter I. --- Introduction --- p.1
Chapter II. --- Turbulent Rayleigh-Benard Convection --- p.5
Chapter 2.1 --- Rayleigh-Benard Convection --- p.5
Chapter 2.2 --- The Convection Equations --- p.6
Chapter 2.3 --- The parameters --- p.7
Chapter 2.4 --- Recent Developments --- p.9
Chapter 2.4.1 --- Heat Transport --- p.9
Chapter 2.4.2 --- Large-scale Circulation and thermal Plumes --- p.11
Chapter 2.4.3 --- Boundary Layers --- p.12
Chapter III. --- Experimental Setup and Methods --- p.15
Chapter 3.1 --- The Apparatus --- p.15
Chapter 3.2 --- The Working Fluids --- p.18
Chapter 3.3 --- Thermal Measurements --- p.23
Chapter 3.4 --- Flow Visualization --- p.26
Chapter IV. --- Heat Transport in Turbulent Convection --- p.29
Chapter 4.1 --- The Non-Boussinesq Effect --- p.30
Chapter 4.2 --- Experimental Results --- p.34
Chapter 4.2.1 --- 1-Pentanol --- p.35
Chapter 4.2.2 --- Triethylene Glycol --- p.36
Chapter 4.2.3 --- Results from Dipropylene Glycol --- p.37
Chapter 4.3 --- Discussion on the Results --- p.38
Chapter 4.4 --- Summary --- p.43
Chapter V. --- Local Temperature Measurements --- p.45
Chapter 5.1 --- Temperature Time Series and Histograms --- p.45
Chapter 5.2 --- Mean Temperature Profiles and Thermal Boundary Layers --- p.55
Chapter 5.3 --- RMS Profiles --- p.58
Chapter 5.4 --- Skewness Profiles --- p.65
Chapter 5.5 --- Summary --- p.68
Chapter VI. --- Measurements on the Viscous Boundary Layers --- p.70
Chapter 6.1 --- Power Spectrum --- p.70
Chapter 6.2 --- Two-Probe Cross-correlation --- p.76
Chapter 6.3 --- Laser Light Scattering --- p.84
Chapter 6.4 --- Summary --- p.90
Chapter VII --- . Conclusions --- p.93
References --- p.97

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"High Prandtl number turbulent convection over rough surfaces." 2004. http://library.cuhk.edu.hk/record=b5896218.

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Chan Ho-Sun = 在粗糙表面的高普朗特數湍流對流實驗 / 陳浩新.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references (leaves 69-72).
Text in English; abstracts in English and Chinese.
Chan Ho-Sun = Zai cu cao biao mian de gao Pulangte shu tuan liu dui liu shi yan / Chen Haoxin.
Abstract (in English) --- p.i
Abstract (in Chinese) --- p.ii
Acknowledgements --- p.iii
Table of Contents --- p.iv
List of Figures --- p.vi
List of Tables --- p.viii
Chapters
Chapter 1. --- Introduction --- p.1
Chapter 2. --- Theories about the Convection --- p.7
Chapter 2.1 --- Rayleigh-Benard convection --- p.7
Chapter 2.2 --- The Convection Equations --- p.8
Chapter 3. --- Setup of the Experimental Environment --- p.15
Chapter 3.1 --- The Convection Cell --- p.15
Chapter 3.2 --- Thermistors --- p.19
Chapter 3.3 --- The Working Fluids --- p.22
Chapter 3.4 --- Thermal Measurements --- p.27
Chapter 3.5 --- Temperature Control Box --- p.28
Chapter 4. --- Heat Transport Measurement --- p.29
Chapter 4.1 --- Correction Procedures --- p.30
Chapter 4.2 --- The Non-Boussinesq Effects --- p.33
Chapter 4.3 --- Experiment Results --- p.41
Chapter 4.3.1 --- Triethylene Glycol --- p.41
Chapter 4.3.2 --- Dipropylene Glycol --- p.45
Chapter 4.4 --- Discussion on the Results of Heat Transport --- p.50
Chapter 4.5 --- Discussion on the Results of RMS Fluctuations --- p.60
Chapter 4.6 --- The data set of pr =1400 --- p.63
Chapter 5. --- Conclusion --- p.65
References --- p.69

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Books on the topic "High Prandtl"

PrettyKids, Deluxe. Happy Birthday Pranit: Beautiful 100 Cute Cartoon Notebook. Personalized Gift for Pranit Trex Dinosaur Cover, 100 Pages of High Quality, 6 X9 , Premium Glossy Finish. Independently Published, 2021.

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Ruban, Anatoly I. Introduction. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199681754.003.0001.

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This book investigates high-Reynolds number flows, and analyses flows that can be described in the framework of Prandtl’s 1904 classical boundary-layer theory, including Blasius’s boundary layer on a flat plate, Falkner–Skan solutions for the boundary layer on a wedge surface, and other applications of Prandtl’s theory. It then discusses separated flows, and considers the so-called ‘self-induced separation’ in supersonic flow, and which led to the ‘triple-deck model’. It also presents Sychev’s 1972 theory of the boundary-layer separation in an incompressible fluid flow past a circular cylinder. It discusses the triple-deck flow near the trailing edge of a flat plate, and then considers the incipience of the separation at corner points of the body surface in subsonic and supersonic flows. It covers the Marginal Separation theory—a special version of the triple-deck theory—and describes the formation and bursting of short separation bubbles at the leading edge of a thin aerofoil.

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Ruban, Anatoly I. Fluid Dynamics. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199681754.001.0001.

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This is Part 3 of a book series on fluid dynamics. This is designed to give a comprehensive and coherent description of fluid dynamics, starting with chapters on classical theory suitable for an introductory undergraduate lecture courses, and then progressing through more advanced material up to the level of modern research in the field. This book is devoted to high-Reynolds number flows. It begins by analysing the flows that can be described in the framework of Prandtl’s 1904 classical boundary-layer theory. These analyses include the Blasius boundary layer on a flat plate, the Falkner-Skan solutions for the boundary layer on a wedge surface, and other applications of Prandtl’s theory. It then discusses separated flows, and considers first the so-called ‘self-induced separation’ in supersonic flow that was studied in 1969 by Stewartson and Williams, as well as by Neiland, and led to the ‘triple-deck model’. It also presents Sychev’s 1972 theory of the boundary-layer separation in an incompressible fluid flow past a circular cylinder. It discusses the triple-deck flow near the trailing edge of a flat plate first investigated in 1969 by Stewartson and in 1970 by Messiter. It then considers the incipience of the separation at corner points of the body surface in subsonic and supersonic flows. It concludes by covering the Marginal Separation theory, which represents a special version of the triple-deck theory, and describes the formation and bursting of short separation bubbles at the leading edge of a thin aerofoil.

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Book chapters on the topic "High Prandtl"

Silano, G., K. R. Sreenivasan, and R. Verzicco. "Numerical Simulations of Thermal Convection at High Prandtl Numbers." In Direct and Large-Eddy Simulation VII, 389–94. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-3652-0_57.

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Segawa, T., M. Sano, A. Naert, and J. A. Glazier. "High Rayleigh Number Turbulence of a Low Prandtl Number Fluid." In Flow at Ultra-High Reynolds and Rayleigh Numbers, 247–57. New York, NY: Springer New York, 1998. http://dx.doi.org/10.1007/978-1-4612-2230-9_16.

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Okino, Shinya, and Hideshi Hanazaki. "Turbulence in a Fluid Stratified by a High Prandtl-Number Scalar." In Sustained Simulation Performance 2017, 113–21. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-66896-3_7.

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Rüdiger, Günther. "Differential Rotation, Meridional Flow and a High-Prandtl Number Solar/Stellar Dynamo." In Stellar Astrophysics, 9–16. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-010-0878-5_2.

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Balcazar, Paul S. "Assessment of Two-Equation RANS Turbulence Models for High Prandtl Number Forced Convection in a Pipe." In Communications in Computer and Information Science, 80–95. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-71503-8_7.

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Sufrà, L., and H. Steiner. "A Priori Assessment of Subgrid-Scale Models and Numerical Error in Forced Convective Flow at High Prandtl Numbers." In ERCOFTAC Series, 411–16. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-42822-8_54.

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Younis, O., J. Pallares, and F. X. Grau. "Effect of the thermal boundary conditions and physical properties variation on transient natural convection of high Prandtl number fluids." In Computational Fluid Dynamics 2006, 813–18. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-92779-2_128.

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Tilgner, A., and F. H. Busse. "Direct Numerical Simulation of High Rayleigh Number Convection in a Rotating and Non-Rotating Spherical Shell: The Prandtl Number Dependence." In Advances in Turbulence VI, 389–90. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0297-8_110.

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Younis, O., J. Pallares, and F. X. Grau. "Effects of Geometrical Parameters and Physical Properties Variation on Transient Natural. Convection and Conduction of High Prandtl Number Fluid in Enclosures." In New Trends in Fluid Mechanics Research, 440–43. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-75995-9_143.

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Engh, Thorvald Abel, Geoffrey K. Sigworth, and Anne Kvithyld. "Mixing, Mass Transfer, and Numerical Models." In Principles of Metal Refining and Recycling, 182–239. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198811923.003.0003.

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We want to eliminate dissolved impurities to another phase: slag, gas, solid, or a molten metal that has limited solubility in the main metal. The various phases may be in the form of droplets, bubbles, particles, or walls. The contact areas with metal should be large. The aim in reactor design and operation is to achieve relatively high velocities and small dimensions. Relations for mass transfer are also included since the behaviour of systems with molten metals may be different from that usually treated in chemical engineering. In the field of turbulence the Prandtl eddy length is important for describing removal to walls. Hydrogen in aluminium and the pick-up of hydrogen in aluminium from water vapour is studied in some detail, measured, and modelled. It is taken into account that hydrogen gas is two-atomic. The approach concerning aluminium may be applied to a range of metals.

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Conference papers on the topic "High Prandtl"

Passaggia, Pierre-Yves, Matthew Hurley, Brian White, and Alberto Scotti. "Poster: Turbulent Horizontal Convection at High Prandtl Numbers." In 69th Annual Meeting of the APS Division of Fluid Dynamics. American Physical Society, 2016. http://dx.doi.org/10.1103/aps.dfd.2016.gfm.p0028.

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Zhou, Bin, Li Duan, Liang Hu, and Qi Kang. "Transition in high Prandtl number buoyant-thermocapillary convection." In International Conference on Experimental Mechnics 2008 and Seventh Asian Conference on Experimental Mechanics, edited by Xiaoyuan He, Huimin Xie, and YiLan Kang. SPIE, 2008. http://dx.doi.org/10.1117/12.839071.

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Venugopal, V., and Sharath S. Girimaji. "Prandtl number effects in high-speed rarefied cavity flows." In THMT-15. Proceedings of the Eighth International Symposium On Turbulence Heat and Mass Transfer. Connecticut: Begellhouse, 2015. http://dx.doi.org/10.1615/ichmt.2015.thmt-15.820.

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Weise, F. K., and S. Scholl. "FALLING FILM EVAPORATION OF PURE LIQUIDS AT HIGH PRANDTL NUMBERS." In Annals of the Assembly for International Heat Transfer Conference 13. Begell House Inc., 2006. http://dx.doi.org/10.1615/ihtc13.p28.130.

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Smith-Pollard, Tracey, and John Burgers. "CFD Solutions of High Prandtl Flows Using Boundary Layer Similarity." In International Congress & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1996. http://dx.doi.org/10.4271/960376.

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Wei, P. S., C. L. Lin, and H. J. Liu. "Scale Analysis of Thermocapillary Weld Pool Shape With High Prandtl Number." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62464.

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The molten pool shape and thermocapillary convection during melting or welding of metals or alloys are self-consistently predicted from parametric scale analysis for the first time. Determination of the molten pool shape is crucial due to its close relationship with the strength and properties of the fusion zone. In this work, surface tension coefficient is considered to be negative values, indicating an outward surface flow, whereas high Prandtl number represents the thermal boundary layer thickness to be less than that of momentum. Since Marangoni number is usually very high, the scaling of transport processes is divided into the hot, intermediate and cold corner regions on the flat free surface, boundary layers on the solid-liquid interface and ahead of the melting front. Coupling among distinct regions and thermal and momentum boundary layers, the results find that the width and depth of the pool can be determined as functions of Marangoni, Prandtl, Peclet, Stefan, and beam power numbers. The predictions agree with numerical computations and available experimental data.

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Nakaharai, H., J. Takeuchi, T. Yokomine, Tomoaki Kunugi, S. Satake, N. B. Morley, and M. Abdou. "MEASUREMENT OF TEMPERATURE DISTRIBUTION OF HIGH PRANDTL NUMBER FLUID FLOW UNDER HIGH MAGNETIC FIELD." In Annals of the Assembly for International Heat Transfer Conference 13. Begell House Inc., 2006. http://dx.doi.org/10.1615/ihtc13.p21.170.

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Ramachandran, Ashwin, Bijaylakshmi Saikia, Krishnendu Sinha, and Rama Govindarajan. "Linear stability of high-speed boundary layer flows at varying Prandtl numbers." In 45th AIAA Thermophysics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2015. http://dx.doi.org/10.2514/6.2015-2320.

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Chen, Huajun, Yitung Chen, Hsuan-Tsung Hsieh, and Taide Tan. "Theoretical Analysis of High Prandtl Number Heat Transfer in Non-Isothermal Pipe Flow." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72405.

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Based on Fourier expansion, an analytical solution is developed for the high Prandtl number heat transfer in both fully developed laminar and turbulent non-isothermal pipe flow. Both of the mathematical expressions of the temperature distribution and the local Nusselt number have been obtained. A parametric study illustrates the characteristics of high Prandtl number heat transfer in non-isothermal pipe flow in detailed. The solutions obtained can be used for the numerical construction of the solution to the more general problems of heat transfer in the developed turbulent wall-bounded shear flows.

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Bergant, R., and I. Tiselj. "The Smallest Temperature Scales in a Turbulent Channel Flow at High Prandtl Numbers." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72495.

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The object of this paper is to perform the numerical simulations of the temperature fields at low Reynolds numbers, i.e. Reτ = 150 and Reτ = 170.8, and at Prandtl numbers, Pr = 1 and Pr = 100. The spatial scales of the velocity field can be successfully described with DNS accuracy, meanwhile the scales of temperature fields decreasing approximately with Pr3/2 and cannot be resolved for entire energy scalar spectra due to the computer limitations. To overcome these obstacles, filtering and damping of the highest temperature wave number modes in homogeneous directions are introduced rather than modeling the unresolved subgrid scales. First, numerical simulations at Pr = 1 are performed in order to make comparison of the temperature field described with DNS accuracy and filtered and damped temperature fields described with coarser numerical grids. Obtained results show that at least first and second order statistics are comparable to the DNS ones. Next step is to analyze this approach at two orders of magnitude higher Prandtl numbers, i.e: Pr = 100. Comparison is a little bit difficult because no real DNS of the temperature fields at such high Prandtl number has been performed so far. But we estimate that results are still accurate at least in the proximity of the wall.

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Reports on the topic "High Prandtl"

Brown, R. A. Thermal-capillary model with axisymmetric fluid flow for analysis of Czochralski crystal growth of high Prandtl number materials: Final report. Office of Scientific and Technical Information (OSTI), September 1987. http://dx.doi.org/10.2172/6237678.

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