## Fluids

#### Finding Coefficient of Discharge of an Orifice Plate

• jaseemharry
Subscriber

I am new to ANSYS Fluent. I want to do the simulation of an orifice plate in the laminar pipe flow. Creating Geometry and simulation was easy. But i don't know how to find the coefficient of discharge. Cd = Actual discharge/Theoretical discharge. How to find these quantities in ANSYS?

I am an absolute beginner. So i am sorry if the question doesn't stand.

Thank you.

• peteroznewman
Subscriber

I wasn't sure of the meaning of theoretical discharge, so I looked this up on Wikipedia

Mathematically the discharge coefficient may be related to the mass flow rate of a fluid through a straight tube of constant cross-sectional area.

For a laminar incompressible flow, the inlet BC has a specific mass flow rate, Fluent can calculate and plot the pressure drop across the orifice, the geometry provides the cross-sectional area of the orifice, and the fluid has a known density.  Don't you have all the quantities to calculate the Coefficient of Discharge?

• raul.raghav
Subscriber

What peter answered is absolutely right.

Adding a little more the discussion, to evaluate coefficient of discharge, Cd:

Cd = Mass flow rate at the outlet / [Area of the outlet * sqrt{2 * density of fluid * (P_in - P_out)}].

So if you used a pressure inlet and pressure outlet boundary condition, all you would need from the CFD simulation is the mass flow rate at the outlet.

• jaseemharry
Subscriber

Thank you guys. Sorry for being a little late to reply.

It works.

Thanks again.