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jasonchang June 6, 2006 08:23

About fluid surface
 
Hi,all

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.

-Robin

jasonchang June 7, 2006 22:30

Re: About fluid surface
 
Hi,Robin

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,

Jason

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
 
Hi,Robin:

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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