fluid viscosity in CEL

  • Last Post 15 July 2019
Goenitz posted this 11 July 2019

Hi all,


I am trying to use fluid viscosity in CEL expression to be used in other formulai.

My material name is 'MSR' and fluid name is 'my'.

I am trying to write expression my.viscosity or my.density, but receiving this error.


P.S. 'my' is Fluid and Particle definitions and  Solid definitions is 'Ni foam'


Expression 'phasedensity*Cf/sqrt(Kp)' depends on a variable 'my.Density' which does not exist.



Expression 'porosity*my.density+(1-porosity)*Ni foam.density' depends on a variable 'my.Density' which does not exist.



Expression 'my.viscosity/porosity' depends on a variable 'my.Dynamic Viscosity' which does not exist.

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abenhadj posted this 11 July 2019

If single phase just use the variables without fluid names.

Best regards, Amine

Goenitz posted this 15 July 2019

The MSR is mixture of gases of methane steam reforming reaction plus passing through a porous medium (Ni foam). Temperature is high so all gases are in gaseous state but Ni foam is in solid state. So it is not a single phase. I wrote expression on following parallel ground of CFX reference guide. System Variable Prefixes

In order to distinguish system variables of the different components and fluids in your CFX model,

prefixes are used. For example, if carbon dioxide is a material used in the fluid air, then some of the

system variables that you might expect to see are:

• air.density - the density of air

• air.viscosity - the viscosity of air

• air.carbondioxide.mf - the mass fraction of carbon dioxide in air

• air | water.surface tension coefficient – the surface tension coefficient between air

and water

• air | water.area density – the interfacial area density between air and water.

abenhadj posted this 15 July 2019

You are referring to the correct passage. Air in the example is a multicomponent phase.

Best regards, Amine