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Palani Velladurai March 16, 2007 04:19

velocities and pressure
Hi guys! I got confused with some basic flow quantities......

consider a channel flow , and my inlet velocity is some 30 m/s for a 2 m length channel.....and I set my outlet as a pressure outlet..In this case setting the values of pressure at te outlet from 0- 100000 Pascal..but I found no change i my velocities....That means ..there is nothing to be related between inlet velo and out.Pressure... or ????? reply me

otd March 16, 2007 09:10

Re: velocities and pressure
What fluid? Density, viscosity = ?

Compressible or incompressible flow?

If incompressible, only the pressure difference counts. Check to see if p_in - p_out is the same for all of your results.

agg March 16, 2007 11:22

Re: velocities and pressure
For the pressure boundary condition you must be setting dp/dx=0 at the inlet. For the two solutions, check the pressure obtained at the inlet. They must be different. The pressure gradient however must be the same (difference between pressures at the inlet and outlet). This mean that the pressure at the inlet adjusts itself to maintain the same flow rate in both cases!

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