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jasonchang June 6, 2006 08:23

About fluid surface

I am use cfx to simulate water filling into a vessel . It's a transient model.

How can I get the surface of water in the filling?I want show it in the animation. Any suggestion will be appreciated. Jason.

Robin June 6, 2006 10:08

Re: About fluid surface
Create an isosurface of volume fraction 0.5 or plot volume fraction on a surface.

To close the walls, follow these steps:

1. Create a contour plot of volume fraction between 0 and 1 with three contour levels. Hide the contour.

2. Create a user surface using the "From Contour" method. Pick the contour plot you created in step 1 and set the contour level to 2 (or 3 depending on whether you picked air or water fraction).

Optionally, if you want combined control of the coloring, create a Surface Group and include your User Surface and Isosurface. Colour to taste and add transparency to wow your friends!

Regards, Robin

Jasonchang June 7, 2006 09:48

Re: About fluid surface
Hi Robin,

Thank you for your help.I'll try it .

By the way ,I have another question: The tank filling model,with air in it ,but the pressure in it is very low,about 1000Pa. The inlet only allow water flow into the vessel .Shoule I use two phase model,set the inlet like this,water Volume Fraction 1,air Volume Fraction 0;homogeneou model;set the air Dispersed phase? Regards,Jason

Robin June 7, 2006 21:32

Re: About fluid surface
Homogenous with free surface should be fine with water as the continuous phase (this doesn't matter so much when free surface option is selected). Volume fraction of 1 for water and 0 for air will introduce only water at the inlet. If you specify a mass flow rate or velocity at your inlet, you will run into problems without an outlet when the tank finishes filling.

Make sure the air phase is compressible.


jasonchang June 7, 2006 22:30

Re: About fluid surface

As the air is very few and compressive,I needn't set an outlet of the vessel.Indeed the inlet is at the bottom and there's no outlet.

I set the isosurface ,contour,user surface and user surface just as you said,but still have some question.

where should the contour be located?

I set the user surface and surface group and nothing appeared.

I am a beginner .Too many things haven't been got. Thank you sincerely. Regards,


Robin June 8, 2006 08:45

Re: About fluid surface
Hi Jason,

You need to walk before you run. Have you been through the tutorials or taken training?

For the tips I gave, locate the contour plot on the outer boundaries. You can select multiple regions by clicking the [...] button beside the location selector and control-clicking on the desired locations.

This is a transient analysis. Are you writing TRN files at each iteration (or at least periodically)? What variables did you include in the trn files?

Regards, Robin

jasonchang June 9, 2006 03:37

Re: About fluid surface

I have been run the simulation,but I think there are still some mistakes I set. e.g,the pressure in the domain is 1000Pa,almost in vacuum.Perhaps I can't use the 'air at 25C' because the density and some other phsical properties is changed.Maybe I should add a new material by myslef.

I wrote TRN files at each iteration ,but not include variables in the trn files.Maybe it is just the reason I failed.

By the way,How to set the air phase compressible? Thank you for having given me so many advices. Regards,Jason

Robin June 9, 2006 09:17

Re: About fluid surface
I don't mean to be rude Jason, but you should really think a little more before you begin. STP means Standard Temperature and Pressure... are you running at Standard Temperature and Pressure.... No! Don't get me started on writing a TRN file and not including variables!

Read some documentation, run a few tutuorials, then come back and ask questions.

If you are a student, pray that your prof is not reading this forum.

Regards, Robin

jasonchang June 9, 2006 20:53

Re: About fluid surface
Thank you all the same. I try it by myself. Regurds,Jason

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