[Ehsan301]

Hi, i'm working on a 2D simulation which contains a sodium flow and it's properties are function of temperature. i used expression to define them but when i run the solver it returns with error code 1 and fatal error on material properties.
when i use other materials like ideal gas air there is no problem so i think the problem is with the material properties.
i used these expressions:
Density : ((1012 [K] )-(0.23*T))*1 [kg m^-3 K^-1]
Dynamic viscosity : (88500 [K] - 94*T)*1 [Pa s K^-1]
Specific Heat Capacity : (1499 [K] - 0.33*T)*1 [J kg^-1 K^-2]
Thermal Expansivity : (20000 [K] + 10*T)*1 [K^-2]
Thermal Conductivity : (112.1 [K] - 0.064*T)*1 [W m^-1 K^-2]
and checked Temp.Extrapolation in material properties.

it's 2D Steady State simulation with velocity inlet and pressure outlet and a fixed temperature wall

Here is the file:
http://www.mediafire.com/file/ygk5oo...ODIUM_FLOW.rar

[evcelica]

Looking at that viscosity expression, Wow!!! That is an incredibly high viscosity! 60 million times more viscous than water!
Your Thermal expansivity is WAY too high as well: 24000 [K^-1]!!!!
You can plot your expressions in CFX pre to check if you have them right. but these are definitely not correct.

Also:
Thermodynamic inconsistencies can arise from defining both density and specific heat as dependent variables.
Try making one of them constant.
You don't need variable density and thermal expansion. the thermal expansion will be ignored and you will use the full buoyancy model instead if you define variable density.
I'd make density constant, and just use the expansion for buoyancy (boussinesq approximation)

[Ehsan301]

Originally Posted by evcelica

Looking at that viscosity expression, Wow!!! That is an incredibly high viscosity! 60 million times more viscous than water!
Your Thermal expansivity is WAY too high as well: 24000 [K^-1]!!!!
You can plot your expressions in CFX pre to check if you have them right. but these are definitely not correct.

i found the properties from an article:



it seems correct when i plot these expressions in cfx but when i use them to define the material even only one of them then the solver will give me error and won't start.
i also tried to use constant values near these, the solver wouldn't give error but it converged so fast and actually it didn't solve anything and gave me empty data.

[Ehsan301]

you are right, it was written 4.15*10^4 for viscosity in the article i found the properties from , but it should be 4.15*10^-4. i think that was the problem.
thanks