An improved numerical algorithm for solution of convective heat transfer problems on nonstaggered grid system

1998 ◽  
Vol 33 (4) ◽  
pp. 273-280 ◽  
Author(s):  
Q. W. Wang ◽  
J. G. Wei ◽  
W. Q. Tao
Author(s):  
R. V. Zhalnin ◽  
V. F. Masyagin ◽  
E. E. Peskova

The present paper is devoted to the construction of a parallel computational algorithm for solving convective heat transfer problems using the discontinuous Galerkin method on unstructured staggered grids. The computational algorithm is implemented on the basis of MPI parallel computing technology. A special feature of the algorithm is that auxiliary variables that occur when the diffusion terms are approximated by the discontinuous Galerkin method are not involved in interprocessor exchange. The developed parallel algorithm is applied to modelling of temperature dynamics in formation with a vertical injection well and hydraulic fracturing. The paper presents the results of a computational experiment and estimates the effectiveness of a parallel algorithm.


Author(s):  
Jennifer van Rij ◽  
Tim Ameel ◽  
Todd Harman

The effects of rarefaction on convective heat transfer and pressure drop characteristics are numerically evaluated for uniform wall heat flux rectangular microchannels. Results are obtained by numerically solving the momentum and energy equations with both first- and second-order slip velocity and temperature jump boundary conditions. The resulting velocity and temperature fields are then evaluated to obtain the microchannel Poiseuille and Nusselt numbers. In addition to the effects of rarefaction, the effects of aspect ratio, thermal creep flow, and viscous dissipation are investigated for locally fully developed Poiseuille and Nusselt numbers. The constant wall heat flux results obtained in this study are compared to constant wall temperature results obtained previously, using the same numerical algorithm, at various aspect ratios including the limiting case of parallel plate microchannels. In addition to supplying previously unreported data on slip flow convective heat transfer and pressure drop characteristics, these results verify the numerical algorithm for more complex future slip flow analyses.


2009 ◽  
Vol 2009 ◽  
pp. 1-27 ◽  
Author(s):  
Abram Dorfman ◽  
Zachary Renner

A review of conjugate convective heat transfer problems solved during the early and current time of development of this modern approach is presented. The discussion is based on analytical solutions of selected typical relatively simple conjugate problems including steady-state and transient processes, thermal material treatment, and heat and mass transfer in drying. This brief survey is accompanied by the list of almost two hundred publications considering application of different more and less complex analytical and numerical conjugate models for simulating technology processes and industrial devices from aerospace systems to food production. The references are combined in the groups of works studying similar problems so that each of the groups corresponds to one of selected analytical solutions considered in detail. Such structure of review gives the reader the understanding of early and current situation in conjugate convective heat transfer modeling and makes possible to use the information presented as an introduction to this area on the one hand, and to find more complicated publications of interest on the other hand.


2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Javier A. Narvaez ◽  
Aaron R. Veydt ◽  
Robert J. Wilkens

There is a critical need for improved coolants for military aircraft applications. The objective of this research is to evaluate nanofluids as potential replacement for the coolant currently used by the Air Force. Alumina/DI water nanofluids were evaluated. It was observed that at the same volumetric flow there was no significant improvement in convective heat transfer. Problems associated with the nanofluids were observed: increase of pressure drop with concentration, particle settling, and especially evidence of vaporization promoted by the nanoparticles. Results raised doubts about the applicability of using nanofluids as alternative coolants for avionic applications.


2021 ◽  
Vol 22 (4) ◽  
Author(s):  
Damian Goik ◽  
Krzysztof Banaś ◽  
Jan Bielański ◽  
Kazimierz Chłoń

We describe an approach for efficient solution of large scale convective heat transfer problems, formulated as coupled unsteady heat conduction and incompressible fluid flow equations. The original problem is discretized in time using classical implicit methods, while stabilized finite elements are used for space discretization. The algorithm employed for the discretization of the fluid flow problem uses Picard's iterations to solve the arising nonlinear equations. Both problems, heat transfer and Navier-Stokes quations, give rise to large sparse systems of linear equations. The systems are solved using iterative GMRES solver with suitable preconditioning. For the incompressible flow equations we employ a special preconditioner based on algebraic multigrid (AMG) technique. The paper presents algorithmic and implementation details of the solution procedure, which is suitably tuned, especially for ill conditioned systems arising from discretizations of incompressible Navier-Stokes equations. We describe parallel implementation of the solver using MPI and elements of PETSC library. The scalability of the solver is favourably compared with other methods such as direct solvers and standard GMRES method with ILU preconditioning.  


Author(s):  
D. J. M. N. Chalhub ◽  
L. A. Sphaier ◽  
L. S. de B. Alves

This paper presents a novel methodology for the solution of problems that include diffusion and advection effects, as naturally occur in convective heat transfer problems. The methodology is based on writing the unknown temperature field in terms of eigenfunction expansions, as traditionally carried-out with the Generalized Integral Transform Technique (GITT). However, a different approach is used for handling advective derivatives. Rather than transforming the advection terms as done in traditional GITT solutions, upwind discretization schemes (UDS) are used prior to the integral transformation. With the introduction of upwind approximations, numerical diffusion is introduced, which can be used to reduce unwanted oscillations that arise at higher Péclet values. This combined methodology is termed the GITT-UDS for convective problems. The procedure is illustrated for a simple case of one-dimensional Burgers’ equation with temperature-dependent velocities. Numerical results are calculated, showing that augmenting the upwind approximation parameter can effectively reduce solution oscillations for higher Péclet values.


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