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## Simulation CFD

Contributor
Posts: 17
Registered: ‎11-26-2012

# concentration calculation from general scalar simulation

197 Views, 3 Replies
09-16-2013 09:52 AM

Hi Guys,

I am trying to study the fluid 1 displacement by fluid 2 using general scalar simulation for a given volume. I have few questions as follows

1. for a given boundary conditions the given volume should be filled in 0.011 sec but when i run it. it takes around 0.05 sec. I dont know why it is taking so long time. can anyone explain.

2. How to calculate the volumes of fluid 1 and fluid 2 after iam done with my simulation using scalar value. or may be concentration of fluid 1 and fluid 2.

Thanking you,

Shoeb.

Product Support
Posts: 960
Registered: ‎08-25-2011

# Re: concentration calculation from general scalar simulation

09-18-2013 02:33 AM in reply to: sshoeb42

Hi Shoeb,

1. What are the fluids and what value are you using as the diffusion coefficient? Do you have Intelligent Solution Control turned on or off?
2. I will have to leave this one to someone else as I do not think we can actually do this. We can meausure the scalar (which you can convert to concentration by hand) on a cut-plane but I'm not sure we can give you a ratio within the fluid volume.

Hopefully that helps you a little and with some more information on point 1 we might be able to help more.

Kind regards,

Jon

Jon Wilde
Contributor
Posts: 17
Registered: ‎11-26-2012

# Re: concentration calculation from general scalar simulation

09-18-2013 07:36 AM in reply to: wildej
Hi Jon,

I took Fluid 1 (air) and fluid 2 (co2) I used the diffusion coefficient recommended i.e., 0.16 cm2/sec. when I used to run the simulation before without using scalar calculation i.e., just for flow calculations I didn't have problem with divergence. but when I started simulating the scalar simulation I had divergence in solution after some time so i have to reduce the vel, pressure, density to 0.4 from 0.5 and also reduced scalar from 1 to 0.9.

I tried running with both intelligent solution control turned on and off. The only difference I found between two that the former stops when the convergence is reached before the time I want it to run I changed to stricter but the convergence reached before the time I told it to run.

Can you just explain how to measure the scalar by hand

Thanking you,
Shoeb.
Product Support
Posts: 960
Registered: ‎08-25-2011

# Re: concentration calculation from general scalar simulation

09-18-2013 07:52 AM in reply to: sshoeb42

Hi Shoeb,

You can capture the scalar on a cut-plane and should be able to convert it to a concentration just using the ratio of Air to CO2. As far as I know, there is no way to do this per volume.

Happy to take a look at your CFZ (support file) if you think it might help.

Thanks,

Jon

Jon Wilde