low velocity but high mach number? it is true!
hi all,
I am modeling a electro-chemical reaction flow in cfx11.0 with velocity about 1.0~2.0 m/s, but the density will change (2~3 times) along the flow channel. When I solve this problem with normal incompressible N-S equation. The solver will stop with error message "the current mach number is **",which is much more than 1.0. How to deal with this problem? Any comment will be appreciate! Thanks. frank |
Re: low velocity but high mach number? it is true!
This is a fairly common error message and could be caused by a number of things: poor initial guess, poor boundary conditions, poor quality grid. I would start by examining all of those first. You could also try setting the expert parameter "max continuity loops = 2" but I've had issues with energy imbalance in the past using this.
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Re: low velocity but high mach number? it is true!
Check you scales. Is the geometry/grid the right size? What about the units on your boundary conditions?
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Re: low velocity but high mach number? it is true!
Thanks for John S and CycLone.
Do the scales and size really effect the this problem, CycLone? The flow channel is solid oxide fuel cell flow channel.The geometry and grid are in 'mm' unit(1.5mm x 1.5mm) and the inlet velocity is 'm' unit(1~2m/s). |
Re: low velocity but high mach number? it is true!
you have to estimate your Re number and also put on the ideal gas option ON
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