CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

Material Properties by expressions

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 28, 2019, 09:58
Default Material Properties by expressions
  #1
New Member
 
Join Date: Mar 2019
Posts: 1
Rep Power: 0
testaccount is on a distinguished road
Hey folks,


i want to simulate the flow of liquid oxygen. In a preliminary simulation i used a constant property liquid and everything worked fine.

Now i want to account for changes in fluid properties. I defined expressions for the density, heat capacity, dynamic viscosity and the thermal conductivity as functions of p and T (pressure and Temperature). I checked the units and the values and they are correct. If i don't setup a table CFX-Pre starts complaining. I tried to start a simulation with and without a table but either way the solver stops immediately.

Is there a major mistake in my setup?
Do i need a table?
I heard about problems when defining density and the heat capacity at the same time but i couldn't find any related threads.

Thanks in advance
testaccount is offline   Reply With Quote

Old   March 28, 2019, 10:27
Default
  #2
Senior Member
 
Join Date: Jun 2009
Posts: 1,869
Rep Power: 33
Opaque will become famous soon enough
The CFX-Solver nearly always creates a table from the fundamentals properties given by expressions.

For example, how would compute Enthalpy from a Cp expression? How would you compute Entropy from expressions for density and Cp?

Thermodynamic properties are not independent, they MUST satisfy the Maxwell relationships; otherwise, the energy balance equations will not work properly.

See ANSYS CFX documentation for a light description of the minimum requirements.
Opaque is offline   Reply With Quote

Reply

Tags
error, expressions, material, properties


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Simple piston movement in cylinder- fluid models arun1994 CFX 4 July 8, 2016 03:54
[Other] Material properties in multi region foam and refining mesh for each region mukut OpenFOAM Meshing & Mesh Conversion 2 October 7, 2013 03:08
Material Properties in COMSOL for different domains with different physics TryMyBest COMSOL 0 March 5, 2013 09:23
Material Properties table? (function of two variables) evcelica CFX 2 October 1, 2012 20:36
Vaiable Material properties Pialisen FLUENT 2 November 29, 2006 14:12


All times are GMT -4. The time now is 00:33.