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Variable physical properties of fluids/solids

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Old   May 11, 2003, 08:23
Default Variable physical properties of fluids/solids
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rosco
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Hi, is Fluent include all the change of physical properties in materials? For example density, Cp, viscosity change with temperature. I don't want Constant physical values for a fluid but all of them.

I have to enter manually the polynomial equation (piecewise linear or polynomial) to relate these facts or is it already included?? Thx a lot.
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Old   May 11, 2003, 11:35
Default Re: Variable physical properties of fluids/solids
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ap
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You have to manually insert polynoms coefficients in the Materials dialog box.

ap
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Old   May 11, 2003, 11:46
Default Re: Variable physical properties of fluids/solids
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rosco
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Oki thx ap They should be put these data in fluent directly, it's a loss of time for us.
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Old   May 11, 2003, 15:37
Default Re: Variable physical properties of fluids/solids
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ap
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Polyomial expressions are not valid in all ranges of their parameters, so a complete database should contain different expressions for the same datum in different ranges. And for a single datum, the solver should decide which expression is valid.

I think it's better to leave the user decide which expression is better to use, even if this is time consuming

However, you can find a complete database integrated in Aspen.

Hi

ap
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Old   May 11, 2003, 15:56
Default Re: Variable physical properties of fluids/solids
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rosco
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My temperature range is quite small [20C to 50-60C] and only for water. I must verify but I think I have all values for density, Cp, k at each temperature so it's not a problem. I'll do probably a piecewise-polynomial because more easy than calculate the polynomial regression.. And I'll save it in propdb.scm to avoid re-type it again and again

I don't know what is ASPEN , I'll do a search on Google

Thx
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Old   May 11, 2003, 16:06
Default Re: Variable physical properties of fluids/solids
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rosco
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piecewise-linear I want to say not polynomial
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Old   May 11, 2003, 16:10
Default Re: Variable physical properties of fluids/solids
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ap
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If you don't want to calculate expressions by yourself, try to look for them in the Perry's Chemical Engineers' Handbook (McGraw Hill).

Hi

ap
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