[vinayak4399]

Hello All,

I want to simulate and find out pressure spike (surge) developed in pipe domain due to sudden closing of outlet.

Pipe inlet :- constant mass flow rate 0.8379 kg/s

Pipe outlet :- Initially open to atm pressure (for 0.75 sec) & after closed as a wall ( for 0.25 sec) / This is done with UDF

Total run is of :- 1 sec

Fluid :- OIL (Density 882 kg/m3 , viscosity 0.0529 Pa.s)

Solver :- Pressure based , Transient simulation.

After run it is observer that pressure spike not generated along the pipe length in domain. May be due to incompressibility of oil.

Can any one help me how to model this problem??
Is any suggestions for solver setting or inlet BC or material properties...

Thanks All

[FMDenaro]

Originally Posted by vinayak4399

Hello All,

I want to simulate and find out pressure spike (surge) developed in pipe domain due to sudden closing of outlet.

Pipe inlet :- constant mass flow rate 0.8379 kg/s

Pipe outlet :- Initially open to atm pressure (for 0.75 sec) & after closed as a wall ( for 0.25 sec) / This is done with UDF

Total run is of :- 1 sec

Fluid :- OIL (Density 882 kg/m3 , viscosity 0.0529 Pa.s)

Solver :- Pressure based , Transient simulation.

After run it is observer that pressure spike not generated along the pipe length in domain. May be due to incompressibility of oil.

Can any one help me how to model this problem??
Is any suggestions for solver setting or inlet BC or material properties...

Thanks All

My opinion is that the incompressible flow assumption cannot be used. You need to solve the density-based formulation for small density variation. Pressure cannot be governed by the elliptic equation, you need to take into account the the closing outlet will generate a pressure wave towards the inlet at a finite velocity.

[vinayak4399]

Originally Posted by FMDenaro

My opinion is that the incompressible flow assumption cannot be used. You need to solve the density-based formulation for small density variation. Pressure cannot be governed by the elliptic equation, you need to take into account the the closing outlet will generate a pressure wave towards the inlet at a finite velocity.

Thanks FMDenaro
I will follow your opinion to use density based solver.
But for small density variation in oil, Is need to use UDF for density property with using oil bilk modulus??