A spectral relaxation method for linear and non-linear stratification effects on mixed convection in a porous medium

RamReddy, Ch.; Narayana, P. A. Lakshmi; Motsa, S. S.

doi:10.1016/j.amc.2015.07.007

Cited by 7 publications

(5 citation statements)

References 17 publications

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“…In this way, it can be said that the thermal stratification significantly affects the heat transfer rate of power‐law fluids besides delaying the boundary layer separation. The results are in tune with the observation made in references [RamReddy et al 17 ; Vasu et al 20 and citations therein].…”

Section: Resultssupporting

confidence: 91%

“…One can refer to the works of Knudsen and Simon 16 for more details. RamReddy et al 17 investigated the effects of linear and nonlinear stratification on mixed convective flow in a porous medium and concluded that the stratification significantly affects the heat and mass transfer rates, in addition with delaying the boundary layer separation (also see the references given there). The numerical modeling and optimization aspect of thermal stratification effect in solar hot water storage tanks is provided by Bouhal et al 18 .…”

Section: Introductionmentioning

confidence: 99%

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Effect of dispersion on thermally stable stratified power‐law fluids over the vertical frustum of a cone in a non‐Darcy porous medium: Flow separation

RamReddy

Srivastav

2020

Heat Trans

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The present problem shares out the influences of convective heating and thermal dispersion on thermally stable stratified power‐law fluid flow over the vertical frustum of a cone situated in a non‐Darcy porous medium. For the first time, it is considered in both aiding and opposing flow cases as it is readily applicable in realistic, practical situations. The local nonsimilarity approach, along with the spectral local linearization method, is used to analyze the fluid behavior and heat transfer within the boundary layer region. In addition, error analysis and comparison with the existing results are also included to validate the obtained results wherever feasible. It is significant to perceive the existence of flow separation in this study as more gain of the velocity of a power‐law fluid is seen for aiding flow case in comparison with the opposing flow case. Also, it is evident from these results that the separation of flow is less in the presence of thermal stratification, but it is more in the absence of thermal stratification. Finally, thermal stratification significantly affects the heat transfer rate of power‐law fluids besides delaying the boundary layer separation.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Effect of dispersion on thermally stable stratified power‐law fluids over the vertical frustum of a cone in a non‐Darcy porous medium: Flow separation

RamReddy

Srivastav

2020

Heat Trans

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“…Spectral methods are successfully applied in studies of wave propagation, meteorology, computational fluid dynamics, quantum mechanics and several other fields [19]. Some works on the transport phenomena can be found in literature involving diffusive [36,67], convective [22,61] and radiative [21,44,46] heat transfer. Spectral techniques applied in these works are varied, adopted according to the geometry, boundary conditions, field of application, and other necessities.…”

Section: Reduced Spectral Methodsmentioning

confidence: 99%

Advanced Reduced-Order Models for Moisture Diffusion in Porous Media

et al. 2018

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It is of great concern to produce numerically efficient methods for moisture diffusion through porous media, capable of accurately calculate moisture distribution with a reduced computational effort. In this way, model reduction methods are promising approaches to bring a solution to this issue since they do not degrade the physical model and provide a significant reduction of computational cost. Therefore, this article explores in details the capabilities of two model-reduction techniques -the Spectral Reduced-Order Model (Spectral-ROM) and the Proper Generalised Decomposition (PGD) -to numerically solve moisture diffusive transfer through porous materials. Both approaches are applied to three different problems to provide clear examples of the construction and use of these reduced-order models. The methodology of both approaches is explained extensively so that the article can be used as a numerical benchmark by anyone interested in building a reduced-order model for diffusion problems in porous materials. Linear and non-linear unsteady behaviors of unidimensional moisture diffusion are investigated. The last case focuses on solving a parametric problem in which the solution depends on space, time and the diffusivity properties. Results have highlighted that both methods provide accurate solutions and enable to reduce significantly the order of the model around ten times lower than the large original model. It also allows an efficient computation of the physical phenomena with an error lower than 10 −2 when compared to a reference solution.

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“…Spectral methods are successfully applied in studies of wave propagation, meteorology, computational fluid dynamics, quantum mechanics and several other fields [9]. Some works on the transport phenomena can be found in literature involving diffusive [19,50], convective [11,39] and radiative [10,24,29] heat transfer. Spectral techniques applied in these works are varied, adopted according to the geometry, boundary conditions and field of application.…”

Section: Introductionmentioning

confidence: 99%

Solving nonlinear diffusive problems in buildings by means of a Spectral reduced-order model

Gasparin

Berger

Dutykh

et al. 2018

Journal of Building Performance Simulation

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This paper proposes the use of a Spectral method to simulate diffusive moisture transfer through porous materials as a Reduced-Order Model (ROM). The Spectral approach is an a priori method assuming a separated representation of the solution. The method is compared with both classical Euler implicit and Crank-Nicolson schemes, considered as large original models. Their performance -in terms of accuracy, complexity reduction and CPU time reduction -are discussed for linear and nonlinear cases of moisture diffusive transfer through single and multi-layered one-dimensional domains, considering highly moisture-dependent properties. Results show that the Spectral reducedorder model approach enables to simulate accurately the field of interest. Furthermore, numerical gains become particularly interesting for nonlinear cases since the proposed method can drastically reduce the computer run time, by a factor of 100 , when compared to the traditional Crank-Nicolson scheme for one-dimensional applications.

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A spectral relaxation method for linear and non-linear stratification effects on mixed convection in a porous medium

Cited by 7 publications

References 17 publications

Effect of dispersion on thermally stable stratified power‐law fluids over the vertical frustum of a cone in a non‐Darcy porous medium: Flow separation

Effect of dispersion on thermally stable stratified power‐law fluids over the vertical frustum of a cone in a non‐Darcy porous medium: Flow separation

Advanced Reduced-Order Models for Moisture Diffusion in Porous Media

Solving nonlinear diffusive problems in buildings by means of a Spectral reduced-order model

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