[chamounet]

hello everyone, i'm new to star-CCM+ and to CFD in general.
i'm currently trying to simulate the pressure drop in a vacuum cleaner hoses and don't really succeed.

I already import my geometry from CATIA, set up the region with the interface region, inlet and outlet of the hose ans set the physics continuum for solid and gas region

I just don't really now what boundary and and phycics value to put in.

my capacity is a flow of 120m^3/h (approximately 12m/s), a depression of -35 000 Pa

i set the boundary for the inlet and outlet to pressure outlet and one of them with a physics value for pressure at -35 000Pa

but the curve for pressure at the inlet stay at 0Pa and the one at the outlet stay at -35 000 Pa.

if you can help me i would be really grateful

[me3840]

It sounds like you put in your pressure values and that's what you got out, what's the problem?

I would not use a pressure-pressure BC though. Generally you should use a massflow inlet - pressure outlet condition, it will converge more easily.

[chamounet]

thanks for the answer, i will try that but I don't know what physics value to enter in the mass flow inlet (if i put the pressure condition on my outlet and the mass flow value on my inlet it will over constraint my model no?)

[me3840]

You listed a volumetric flow rate above, why can't you use that?

[rajeev50588]

Originally Posted by chamounet

hello everyone, i'm new to star-CCM+ and to CFD in general.
i'm currently trying to simulate the pressure drop in a vacuum cleaner hoses and don't really succeed.

I already import my geometry from CATIA, set up the region with the interface region, inlet and outlet of the hose ans set the physics continuum for solid and gas region

I just don't really now what boundary and and phycics value to put in.

my capacity is a flow of 120m^3/h (approximately 12m/s), a depression of -35 000 Pa

i set the boundary for the inlet and outlet to pressure outlet and one of them with a physics value for pressure at -35 000Pa

but the curve for pressure at the inlet stay at 0Pa and the one at the outlet stay at -35 000 Pa.

if you can help me i would be really grateful

Star CCM+ provides you with different boundary conditions. In your case i feel you can try out with the following BC's
a) Mass Flow Inlet and Pressure Outlet: Make sure that you convert the volume flow rate into mass flow rate based on density
b) Velocity Inlet and Pressure Outlet: I see that you have velocity as well,so you can try using that too and see the results..