| 1. |
|
|
| 2. |
- Yan, Zhenghua
(författare)
-
A fast spectral approximation of narrow-band model for thermal radiation calculation
- 2004
-
Ingår i: Numerical Heat Transfer Part B: Fundamentals. - : Informa UK Limited. - 1040-7790 .- 1521-0626. ; 46:2, s. 165-178
-
Tidskriftsartikel (refereegranskat)abstract
- A fast spectral approximation of a narrow-band computer model is proposed for prediction of thermal radiation in a generally nonisothermal and nonhomogeneous combustion environment. The approximation is made by assuming each discretized spatial element along a line of sight to be locally "gray" within each small narrow-band spectrum interval. For each spatial element, the local equivalent spectral absorption coefficient of the combustion products, including carbon dioxide, water vapor, and soot, is calculated based on formulas from the narrow-band model. Compared with the previously developed fast narrow-band model, FASTNB, which is an order of magnitude faster and gives almost exactly the same result as Grosshandler's original narrow-band model RADCAL, this approximation method provides calculation result with small deviation at substantially faster speed. Furthermore, the speed-up ratio increases linearly with the number of discretized spatial elements along a line of sight. This makes this approximation method particularly useful in computational combustion, where the grid number used in computation is steadily becoming larger and larger as the computation goes toward large eddy simulation (LES) and direct numerical simulation (DNS).
|
|
| 3. |
- Yan, Zhenghua
(författare)
-
A numerical study of effect of initial condition on large eddy simulation of thermal plume
- 2003
-
Ingår i: Numerical Heat Transfer Part B: Fundamentals. - : Informa UK Limited. - 1040-7790 .- 1521-0626. ; 43:2, s. 167-178
-
Tidskriftsartikel (refereegranskat)abstract
- Large eddy simulations of thermal plume in two different scenarios have been carried out using a self-developed parallel computational fluid dynamics (CFD) code, SMAFS (Smoke Movement And Flame Spread), with subgrid-scale turbulence modeled using the Smagorinsky model. Two different initial conditions were used in the simulations, and the results were compared to show that the initial condition has a significant effect on the prediction of the plume's evolution behavior. The filtered governing equations were discretized using the finite-volume method, with the variables at the cell faces in the finite-volume discrete equations approximated by a second-order bounded QUICK scheme and the diffusion term computed based on the central difference scheme. All the computations were explicitly time-marched, with the momentum equations solved based on a second-order fractional-step Adams-Bashford scheme and the enthalpy computed using a second-order Runge-Kutta method. The Poisson equation for pressure from the continuity equation was solved using a multigrid solver.
|
|
| 4. |
|
|
| 5. |
- Yan, Zhenghua
(författare)
-
Parallel computation of turbulent combustion and flame spread in fires
- 2002
-
Ingår i: Numerical Heat Transfer Part B: Fundamentals. - 1040-7790. ; 39:6, s. 191-208
-
Tidskriftsartikel (refereegranskat)abstract
- A parallel procedure based on a single-program, multiple-data (SPMD) algorithm is presented for parallel computing of turbulent combustion and flame spread in fires. The computation is based on modeling of radiative turbulent reacting flow and pyrolysis of solid fuel. With angular domain decomposition applied to the parallel computing of radiation and spatial domain decomposition to the computation of nonradiative turbulent reacting flow and solid fuel pyrolysis, the whole computation is distributed among a group of concurrent tasks, which communicate with each other through a message-passing interface library. Using this procedure, a self-developed computational combustion code has been parallelized on both a multiprocessor PC and a symmetric multiprocessor (SMP) system, SGI Origin 2000. The parallelization was verified by comparing the parallel results with sequential results. The performance of the parallel procedure was evaluated using various test cases. As expected, the efficiency of parallelism varies with both computer architecture and case scenario. In general, good efficiency was obtained.
|
|
