scholarly journals Hydrothermal Behavior of Transient Fluid Flow and Heat Transfer Through a Rotating Curved Rectangular Duct with Natural and Forced Convection

2020 ◽  
Vol 7 (4) ◽  
pp. 501-514
Author(s):  
Ratan Kumar Chanda ◽  
Mohammad Sanjeed Hasan ◽  
Md. Mahmud Alam ◽  
Rabindra Nath Mondal
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Steady State ◽  
Convective Heat Transfer ◽  
Secondary Flow ◽  
Convective Heat ◽  
Time History ◽  
Rectangular Duct ◽  
Chaotic Flow ◽  
Negative Direction

The present work explores a spectral-based computational study on hydrothermal behavior of transient fluid flow with natural and forced convective heat transfer through a rotating curved rectangular duct of strong curvature. The outer wall of the duct is heated while the inner wall cooled, the other walls being thermally insulated. The system rotates about the vertical axis in the positive and negative direction for the Taylor number (-1000≤Tr≤1000) with a constant non-dimensional pressure gradient force, the Dean number Dn = 2000. Time-history analysis is performed and fluid characteristics are well determined by depicting the phase space of the time-history result. It is found that the chaotic flow turns into steady-state flow through multi-periodic and periodic oscillating flows, if Tr is increased either in the positive or in the negative direction. Streamlines of secondary flow and isotherms are obtained at some specific values of Tr, and it is found that the time-dependent flow consists of asymmetric 2- to multi-vortex solutions. Vortex structure of secondary flows is obtained for physically realizable solutions and it is found that maximum 8-vortex is obtained for the chaotic solution while 2-vortex for the steady-state solution. Nusselt number as well as temperature gradient is calculated as an index of heat transfer, and it is found that convective heat transfer is significantly enhanced by the secondary flow; and the chaotic flow, which occurs relatively at small Tr, boosts heat transfer more effectively than the steady-state or other solutions. Finally, our numerical results have been validated with the experimental outcomes and it is found that there is a good agreement between the numerical and experimental investigations.

scholarly journals Data-Driven Reduced-Order Modeling of Convective Heat Transfer in Porous Media

Fluids ◽  
2021 ◽  
Vol 6 (8) ◽  
pp. 266
Author(s):  
Péter German ◽  
Mauricio E. Tano ◽  
Carlo Fiorina ◽  
Jean C. Ragusa
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Porous Media ◽  
Steady State ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Data Driven ◽  
Reduced Order ◽  
Medium Formulation ◽  
Flow Resistances

This work presents a data-driven Reduced-Order Model (ROM) for parametric convective heat transfer problems in porous media. The intrusive Proper Orthogonal Decomposition aided Reduced-Basis (POD-RB) technique is employed to reduce the porous medium formulation of the incompressible Reynolds-Averaged Navier–Stokes (RANS) equations coupled with heat transfer. Instead of resolving the exact flow configuration with high fidelity, the porous medium formulation solves a homogenized flow in which the fluid-structure interactions are captured via volumetric flow resistances with nonlinear, semi-empirical friction correlations. A supremizer approach is implemented for the stabilization of the reduced fluid dynamics equations. The reduced nonlinear flow resistances are treated using the Discrete Empirical Interpolation Method (DEIM), while the turbulent eddy viscosity and diffusivity are approximated by adopting a Radial Basis Function (RBF) interpolation-based approach. The proposed method is tested using a 2D numerical model of the Molten Salt Fast Reactor (MSFR), which involves the simulation of both clean and porous medium regions in the same domain. For the steady-state example, five model parameters are considered to be uncertain: the magnitude of the pumping force, the external coolant temperature, the heat transfer coefficient, the thermal expansion coefficient, and the Prandtl number. For transient scenarios, on the other hand, the coastdown-time of the pump is the only uncertain parameter. The results indicate that the POD-RB-ROMs are suitable for the reduction of similar problems. The relative L2 errors are below 3.34% for every field of interest for all cases analyzed, while the speedup factors vary between 54 (transient) and 40,000 (steady-state).

Fluid flow and convective heat transfer in flat microchannels

2009 ◽  
Vol 52 (5-6) ◽  
pp. 1337-1352 ◽  
Author(s):  
Omar Mokrani ◽  
Brahim Bourouga ◽  
Cathy Castelain ◽  
Hassan Peerhossaini
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Convective Heat Transfer ◽  
Convective Heat
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