|
[Sponsors] |
Finite-rate H2-AIR chemistry in 1D supersonic flow |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
November 12, 2008, 10:43 |
Finite-rate H2-AIR chemistry in 1D supersonic flow
|
#1 |
Guest
Posts: n/a
|
Hi all,
I have implemented a quasi-1D supersonic combustor-code for scramjet applications with an implizit 2nd-Order-Upwind finite differences discretization of the unsteady conservative Euler equations, coupled with the conservation equations for the spezies concentrations. The solver shows very good stability and quick convergence (< 500 timesteps) for ideal gas or equilibrium chemistry using CFL-numbers in the range of 1-2. But for finite-rate chemistry, the timesteps have to be very small (CFL < 1e-3), because of the chemical source term, which leeds to extrem numbers of timesteps (<50000) until convergence is acieved. I wonder if this behavior is normal, or something's wrong with my code (the solution looks OK). Is there any possibility to accelerate the solver, or to increase the timestep, so that the chemical source terms do not result in an unstability. Thanks for any advice. Cheers Daniel |
|
November 13, 2008, 05:44 |
Re: Finite-rate H2-AIR chemistry in 1D supersonic
|
#2 |
Guest
Posts: n/a
|
Daniel,
It is quite usual that the kinetics prescribe small time step. One way to accelerate the solution is to switch off the reaction and run to convergence, then switch it on, reduce the time step as necessary and restart. I hope this helps, Rami |
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Target Mass Flow Rate | Nitin | FLUENT | 9 | June 17, 2017 11:30 |
Ansys Fluent UDF - for Data Center Air flow management | kedarjan | Fluent UDF and Scheme Programming | 13 | November 13, 2013 05:20 |
target flow rate: varying results | Ryan | FLUENT | 3 | January 9, 2008 14:54 |
particle, parcel and mass flow rate balance | flybird | FLUENT | 0 | May 24, 2007 11:44 |
Modeling reduced flow rate in 2D | Tom Smith | FLUENT | 2 | April 27, 2007 10:04 |