Discussion Forum

Hello
I'm working with water at supercritical conditions and am trying to configure the properties of this in comsol, I'm modifying the properties are the density (rho) in comsol, heat capacity (cp), thermal conductivity (k) and viscosity (etha) the problem is that I have such data on the density and temperature at a pressure of 24 MPa, the METI data in Material> Water> basic (def)> and I comsol interpolation curve plotted me very well, but when I run the simulation in the model that I have integrated the turbulent flow model (ke) and heat transfer fluids, generates an error saying that the matrices Na ... not converge.

perform a polynomial regression of degree 6 to enter it in comsol in Material> Water> basic (def)> piecewise shift 3 (rho) with the following equation

164945.1013728440-1590.8033424291 * T * T ^ 1 ^ 2 6.2306828798-1.2604555138E-2 * T ^ 3 1.3899313851E-5 * T ^ 4-7.9433978593E-9 * T ^ 5 1.8438357144E-12 * T ^ 6

temperatures between 318 642 and 1023.53 and I generated a curve different from that of being but I run the simulation and not an error converges with pardiso.

when you put a comsol polynomial regression of order 4, the graph is not very accurate but the model converges

I want to know how to add the trend of the density of water at supercritical conditions either piecewise (regression) or Interpolation (X and Y coordinates).

attachment behavior graph the density of water at supercritical conditions, here are the values ​​of this curve and the results that throws me comsol.

thanks

Juan Sebastián