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Old   January 9, 2004, 02:49
Default variable density water
  #1
Atit Koonsrisuk
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I am using CFX-5.6. I choose 'Water (saturated liquidX at 100C' from the template as the fluid domain. Generally, I have two options. Enter the numerical value of density, or enter the expression of density as the function of temperature and/or pressure. My question is: I simply enter the numerical value of density. After the solving of CFX-Solver, I found the variation of temperature in the domain from 308 to 650K. However the density of fluid is constant at 958 all over the domain. This seem incorrect, doesn't it? Anybody have an answer? Thank you very much.

Atit
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Old   January 9, 2004, 15:10
Default Re: variable density water
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Atit Koonsrisuk
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I try to use 'water (saturated liquid) at 100C' with the definite numerical value of density, but I tick the checkbox 'depends on temperature' also. I got the same result as the result from the case that I didn't tick the checkbox. If nothing is different, why don't this checkbox turn to gray when we enter the numerical value? It should be, in my humble opinion, to avoid confusion.

Atit Koonsrisuk
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Old   January 9, 2004, 15:10
Default Re: variable density water
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Atit Koonsrisuk
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This time I enter the density as the expression in the form of function of temperature, like 87 + 1.87*T - 9.5*T^2 + 1.4*T^3 but I didn't tick the checkbox 'density depends on temperature'. I got the exact result as simply entering the certain value of density (first and second case) Even we enter the expression of density as the function of temperature, but not tick it as the function of temperature, the density will be constant, isn't it? Thank you very much.

Atit Koonsrisuk
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Old   January 10, 2004, 12:15
Default Re: variable density water
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Neale
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Atit,

Try it again, check the flow solver output file and make sure you didn't make a simple mistake. I've done this plenty of times in 5.6 and it works just fine.

Neale.
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Old   January 11, 2004, 12:51
Default Re: variable density water
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Atit Koonsrisuk
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Dear Neale, Try which case? because, in the above mails, I present that I try so many cases. Thank you.

Atit
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Old   January 13, 2004, 20:52
Default Re: variable density water
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Neale
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Try the last case again, or just check carefully check the flow solver output file. Do you see your expression for density in the command file output?

Neale
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