Turbulence models for CFD in the 21st century
by
Brian Spalding, of CHAM Ltd
October, 2000
Invited lecture presented at ACFD 2000, Beijing
Example 3. The influence of the number of fluids on the predicted rate
of smoke generation in a gas-turbine combustor.
- Predictions of the smoke-production rate have been made with
various population-grid finenesses.
- Some results are contained in the following table.
| number of fluids | production rate |
comments |
| 1 | 6.09 | much too high |
| 3 | 1.22 | much too low |
| 5 | 3.65 | getting close |
| 10 | 3.99 | still varying |
| 20 | 3.32 | very close |
| 100 | 3.23 | presumed correct |
- Since:
- computer time increases with the number of fluids, and
- reaction-rate constants are not known with great accuracy
one could conclude that a coarse population grid (say 10 fluids)
might suffice.
- Of course, the necessary number of fluids will vary from case to case.