Hi, I'm investigating numerically flow characteristics, heat transfer and combustion process in a tangentially fired 200MW boiler furnace.Now,I encounter some problems1)the iteration velocity is very very slow,about 30 step per an hour,the grid size is 38x40x133;(2)the convergence is very difficult,also. Anybody has some advices for me? Thanks, Kay

(1). There are several solutions to this: (2). Use faster computers to do simulation, (3). Use coarse mesh and first-order method to speed up the calculation (for now), (4). Use other codes to do the simulation. (5). Isolate the problem area by building up the model step-by-step. That is, simple geometry, simple cold flow, turbulent flow, reacting flow, more realistic geometry. In this way, you will be able to isolate the problem area. Good Luck.

1. '30 step per an hour' is dependent on the computer. For my case, with about 200K cells(similar to yours), 30~40 step per an hour was general case for furnace combustion simulation with my 800M-CPU personal computer.

2. It is very very general that convergence is difficult for oil or coal combustion. Sometimes, under-relaxation parameter can control convergence/divergence.

Sincerely, Jinwook