# 2 velocity vectors

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 June 19, 2007, 13:16 2 velocity vectors #1 ashish Guest   Posts: n/a Dear all, I am solving a free surface flow problem using inhomogeneous model. When i plot the velocity vectors i can see single velocity vectors on vertex points. When i export the velocity vectors as .dat files and plot it in MATLAB using quiver command it gives error called duplicate data points in MATLAB, however it still plots the vectors. However when i look closely i can see there are two velocity vectors coming out from a single point. This gives error while calculating the stream function in the flow. Any idea why we see the two velocity vectors in MATLAB plotting, but not in CFX-POST ? Thanks, Ashish

 June 19, 2007, 14:27 Re: 2 velocity vectors #2 Johnson Guest   Posts: n/a Hi, inhomogeneous free surface has a velocity field for each phase at each location. You should check the variables in your export file - I suspect you have both fields there - and export only the ones you want. Johnson

 June 19, 2007, 18:13 Re: 2 velocity vectors #3 Glenn Horrocks Guest   Posts: n/a Hi, As Johnson said, there is an independent velocity field for both phases when you select inhomogeneous. That is why you can see two vectors at each point. Most free surface flows can be modelled with homogeneous velocity fields. Then the velocity field is shared for all phases. Should run much faster too, with heaps less memory. Have a read of the documentation about multiphase flows including the best practises guide. Glenn Horrocks

 June 19, 2007, 18:32 Re: 2 velocity vectors #4 Ashish Guest   Posts: n/a Hi Johnson and Glenn, Its true that we have 2 variables at each point for both the phases. But if i export just *.superficial velocity X, *.superficial velocity Y on a plane, i think it should only have velocity field for * fluid and not the other one. I have run homogeneous model, i wanted to compare the results with inhomogeneous model. Thanks, Ashish