CFD Online Discussion Forums

CFD Online Discussion Forums (
-   FLUENT (
-   -   why it doesn`t change (

grzesiek February 19, 2006 05:26

why it doesn`t change
hi i trying to heat a tank filled with water. boudary condition: bottom wall temperature 500K, water temperature 300K, pressure of water 1013hPa. Iterations doing well, residuals too but after iterations density doesn`t change. Why. In real density of water change with temperature isn`t ? so why it doesn`t change in my model. Im using: unstady, VOF with body implict..., g=9.81m2/s. time step size 0,001s, number of time steps 100000 regards

Kharicha February 21, 2006 03:43

Re: why it doesn`t change
You have to explicitly include the density function of temperature the material data.....

Fluent will not change it if you use a fixed density!!

grzes February 21, 2006 06:58

Re: why it doesn`t change
Ok Thank you. I`ve already made an UDF and now everything seems to be ok. regards Grzesiek PS. Mabby you know what to do to have a specific heat changes with temperature changes. I`ve heard that "cp" is the only properties which can not be defined by UDF and must be constant. But what to do when it is a function of temperature and concentration ?

Kharicha February 22, 2006 02:59

Re: why it doesn`t change
Well you are right, it is strange that C_p cannot be modified with an UDF...

but you can use a piecewise-linear function of temperature...or polynomial function of temperature....I am sure you can find what you need

All times are GMT -4. The time now is 03:03.