Learning Forum

[tejesh.nagappa-devdas]

I'm working on a flow meter to calculate angular rotation rad/sec. I'm comparing it with physical model.
I'm using 6DOF dynamic mesh. I have provided all the inputs but i'm getting angular velocity of 175 rad/s. The physical model gets 137 rad/s. Am I doing something wrong with my simulation?

 

[Federico]

There could be several reasons for this. Could you provide more details about your setup? Do you have the right mass and moment of inertia set up? What is the working fluid?

How does the rest of the flow look relative to what you expect?

[tejesh.nagappa-devdas]

Yes, I have viewed the mass of the rotor and MOI from solidworks. The mass is 0.00034g and Izz is 1.34e-9. The working fluid is water. I'm calculating the change in angular motion from motion history. Everything works perfectly, however, I'm getting 27% more angular velocity than the physical model. I know I haven't considered any friction components but I'm fairly new to this so I have no idea what I'm missing.

[Federico]

What are you comparing this to? Another simulation? Experimental results?

Are you modeling water as a compressible liquid? Or with constant density? The latter may result in pressure spikes which could potentially affect your results.

[tejesh.nagappa-devdas]

I'm comparing this to physical flowmeter and another research paper. I'm calculating K meter factor in terms of pulses/litre.

Its constant density and fluid is water. Can you advice me on this?

[Federico]

Constant density fluids lead to effectively infinite wave speeds, which in turn may result in spurious pressure spikes that will affect the resulting force on your rotor.

I would suggest using the compressible liquid formulation for water. 

[tejesh.nagappa-devdas]

Thank you for the suggestion. However, I have not seen any changes in the angular velocity. Does mesh play any role in accuracy of the results?

[Federico]

Yes, having a good mesh may also affect results