|March 15, 2013, 05:44||
Join Date: Nov 2012
Posts: 4Rep Power: 4
I am solving concentration using diffusion equation and for the convection term I need the velocity (U) . but after 2 seconds, the velocity remains constant (steady) and solving it anymore is just wasting time. Does anyone know how can I read phi after 2 second and continue without solving U anymore?
|March 15, 2013, 06:29||
Join Date: Sep 2009
Posts: 790Rep Power: 13
I don't know how important your start-up phase is (I assume it isn't important), but you can
*write a solver that first calculates the velocity field, and afterwards calculate the diffusion/convection.
* update the present solver with an if( t>2 ) around the solution step for U
* use a solver for flow first, then switch to a seperate solver for convection/diffusion.
|March 21, 2013, 16:32||
Join Date: Dec 2010
Posts: 60Rep Power: 6
A not so elegant but very fast way would be, to write a if statement around the #include "uEqn.H" or the code where you solve the momentum equation. You should also stopp solving the pressure correction.
This approch increases the computational work by one if statement every iteration, wouldn't be very flexible and only valid if U and p are constant after some time. But it is done within a minute.
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