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-   -   compressible flow - WATER !! (http://www.cfd-online.com/Forums/main/14282-compressible-flow-water.html)

Bohis October 22, 2007 04:00

compressible flow - WATER !!
 
Hi mates, Im dealing with single phase problem. The fluid is liquid. Therere two pressure inlets. One is a constant value and the other is time-dependent sinusoidal pressure declared in UDF. Because of fast unsteadiness the water density is pressure-dependent (also UDF)The UDF is shown below:

/************************************************** ***************** periodic boundary condition - pressure, density ************************************************** ******************/

#include "udf.h"

DEFINE_PROFILE(unsteady_pressure,thread,position) { face_t f; real t = CURRENT_TIME;

begin_f_loop(f,thread)

{

F_PROFILE(f,thread,position)=100e+05+900e+05*sin(1 0000*3.141592654*t);

} end_f_loop(f,thread) } DEFINE_PROPERTY(cell_density,cell,thread) { real ro; real p = C_P(cell,thread);

ro = 998/(1.0-(p-101325)/2.2e+09); return ro; }

Im using segregated solver. If using just time-dependent pressure, it is O.K. If using also pressure-dependent density,it is immediately diverging.

Could you look up any problem?

Thanks in advance!! Jan


Zhaohui Lu May 24, 2011 19:26

Hi Jan,

Have you fixed the problem above?I also have very similar truble with you. the compressible liquids or air are hard be computed.

thanks
zhaohui


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