Learning Forum

[lauren steels]

Hi,

Im working on modelling fluid flow down an incline plane (60 degree inclination angle) and am wanting to colour my isosurface to show the film thickness using cfd post. Ive been trying to rotate the geometry 60 degrees so that it lines up with the coordinate frame meaning i can just use the Z variable for the colour, but i cant seem to do this. Ive also made a new coordinate frame in the hopes i could calculate the Z variable based on this new coordinate frame but cant work it out either.

Any help would be hugely appreciated.

[Rob]

Which solver are you using? Are you using a film or multiphase model? Are you rotating the domain in the geometry or solver? 

Displaying coordinate (or coordinate - value) is a valid approach so it's a case of figuring out what's not working. 

[lauren steels]

Hi Rob, thanks for your reply! Im solving on fluent using a VOF multiphase model. The domain is rotated in the geometry. 

[Rob]

If you create an isosurface in Fluent how does it look when coloured by coordinate? 

[lauren steels]

If I colour using the Z coordinate it looks like this (the geometry is rotated -60 degrees about the x axis). 

[Rob]

If the film is flowing along that wall won't the thickness be in the y direction? I'm not sure what I'm looking at - try a 3d isometric view & add arrows to show what's going on. 

[lauren steels]

Sorry, here is a better view.

[lauren steels]

[Rob]

It may be easier to rotate the domain in Fluent to align with y & z and then alter the gravity vector to suit. The thickness is then whichever of y or z is normal to the surface. Otherwise you'll need an expression in CFD Post to do the trigonometry to get the film thickness (function of y & z) against the wall position (function of y & z). 

If you just rotate the domain the data moves with the mesh so you shouldn't need to do any additional iterations. 

[lauren steels]

I wasnt aware that you could rotate the domain in fluent so have done that now and it is working. Thanks so much for the help!