3 Replies Latest reply on Dec 20, 2010 6:28 PM by Joe Galliera

# how to pressure drop information from flow analysis?

I am new to SolidWorks and am working on a school project.  I am analyzing a simple ball valve.  I created the flow and such, but the only results that it is showing are the velocity results.  I am looking to analyze the pressure drop from the inlet to the outlet.  In the help menu it states that you can retain this kind of information from the analysis.  How do I get to the pressure drop information?

Thanks

• ###### Re: how to pressure drop information from flow analysis?

create two goals : one at the inlet (pressure) and another one at the outlet (pressure).

Pressure drop is the difference between them.

• ###### Re: how to pressure drop information from flow analysis?

Better yet use an Equation goal and have it calculate the pressure difference for you directly.  One of your boundary conditions should be a pressure condition, and I'm assuming that since you want to calc the pressure difference that the other one is a flow condition.  First you will need to create a Surface goal of pressure (avg static) and then you can use that in the Equation goal.  Now define an Equation goal (this gets added to the list of available goals after you define one goal), and then select that Avg Static Pressure Surface goal and subtract from that the Pressure boundary condition by selecting it from the tree, see the attached pic.

Bonus: If you do not have a pressure boundary condition, you are probably doing an external flow problem.  You can select the "Input Data" label from the tree and you can then use the ambient pressure that was defined in the setup.

• ###### Re: how to pressure drop information from flow analysis?

If you want to get an accurate pressure drop, you will have to add more geometry before and after the valve.  This will simulate more closely what would be done on a test bench; moreover, you do not want to measure the pressure where you may have a recirculation zone, you want to measure it after the flow as reattached to the full pipe diameter and has normalized back to linear pressure drop as you would in a pipe with no obstruction.  The attached PDF pretty much summarzies what I wrote; this is the true way to get the pressure drop.  If you assume that the linear pressure drop in the pipe is small, then you can use the method I explained above in my first reply.

If you are calculating a valve, then what you really want to do is calculate the Cv.  Look at this post for instructions.Flow coefficient, Cv

You can also take a look at my Ball Valve model from 2009 version.  I used this in helping Inline Industries, the owners of the ballvalve.com domain, to calculate Cv properly with Flow Simulation.