Analysis of the LTNE and LTE system with thermal gradients and a heat source in a fluid layer overlying on porous layer

• Published in: Journal of thermal analysis and calorimetry Vol. 149; no. 14; pp. 7579 - 7592
• Main Authors: Varalakshmi, K. B., Manjunatha, N., Sumithra, R., Gangadharaiah, Y. H., Alqahtani, A. S., Malik, M. Y., Punith Gowda, R. J.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.07.2024; Springer Nature B.V
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Convection cooling; Heat generation; Inorganic Chemistry; Liquid phases; Measurement Science and Instrumentation; Permeability; Physical Chemistry; Physical properties; Polymer Sciences; Porous media; Solid phases; Step functions; Temperature gradients; Corrected internal Rayleigh numbers; Heat source; Composite layer; LTNE; Thermal gradients
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-024-13334-x

Convective heat transport in permeable media has been widely modeled using the local thermal non-equilibrium (LTNE) model. The majority of earlier LTNE-based models take temperature interactions between the fluid and solid phases into consideration. The present investigation delves into the intricate dynamics of Darcy–Rayleigh–Bènard (DRB) convection occurring within a liquid layer situated above a porous layer, wherein thermal gradients and heat generation play a pivotal role. This research examines the effects of many types of thermal gradients, including parabolic, step function (SF), linear, piecewise linear heated from below (PLHB), inverted parabolic, and piecewise linear cooled from above (PLCA). A fluid layer sits on top of a porous layer in the composite layer that makes up the system. The porous medium has achieved complete saturation with the identical fluid. The observed system demonstrates the manifestation of LTNE phenomena. Furthermore, the composite layer is constrained horizontally due to the presence of adiabatic stiff peripheries. The explanation to the aforementioned issue is obtained by employing the perturbation approach via analytical methodologies. The ongoing research is focused on exploring various physical parameters in order to examine the underlying physical implications that uphold the phenomenon of LTNE, employing the utilization of diagrammatic representation. A juxtaposition is drawn between the results derived from manipulating various constraints, including the temperature expansion ratio of the liquid phase, the corrected internal Rayleigh numbers, the thermal ratio, the diffusivity ratio of the liquid layer, and the permeable layer, within the framework of the LTNE configuration, and those obtained within the Local Thermal Equilibrium (LTE) regime. The depth ratio is a key factor in the onset of DRB convection, and higher depth ratio values which indicate porous layers that predominate in composite layered systems have a noticeable impact on all variables under investigation.