CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT

Anistropic thermal conduction in Fluent 6.2

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Search this Thread Display Modes
Old   November 23, 2006, 21:07
Default Anistropic thermal conduction in Fluent 6.2
Posts: n/a
Hi fluent users

I have a long list of questions in making the anisotropic thermal conductivity work in fluent 6.2. I'd greatly appreciate your input into this.

Problem Set-up: This is a case study with pure heat diffusion from a source in a circular domain. The source is located in the center of the domain. A UDF imparts anisotropic heat diffusion coefficients in some volumes near the source. This is an unsteady problem. Over time, the species diffuses NOT asymmetrically and no matter what the extent of anisotropy is, the species distribution is symmetric. This is not what one would expect. In addition, the inbuilt panel for specifying the anisotropic tensor components (XX, YY, XY, YX) yields the same result (homogenous circular contours as against anisotropic elliptical contours). The question I have is: Is the anisotropic diffusivity really taken into calculation through a single UDF I specify for the single UDS in enable to make the thermal conductivity anisotropic.

1. What is the typical range of values for Kxx, Kyy, Kxy and Kyx in the anisotropic thermal conductivity tensor matrix? Are the units of the tensor components given in W/m-k?

2. Is this an Eigenvalue matrix or the regular thermal conductivity tensor? 3. Can it always take off-diagonal elements or the tensor is assumed to lie in its principal axis so that only the pivots really influence the problem though the user inputs the off-diagonal elements? 4. Can the off-diagonal elements be negative? 5. Can the thermal conductivity tensor be non positive-definite (I don't think so)? 6. What is the typical range of value of the pre-multiplier? Is the pre-multiplier a product of density and thermal conductivity diffusivity? Or, what is the physical significance of the pre-multiplier and in what way it differs from the thermal diffusivity in the panel? 7. How does the tensor relate mathematically with the thermal diffusivity (K) value of the species in the material property panel apart from the UDS diffusivity? 8. It seems that the anisotropic panel (default) is not working at all or I still do not see the big picture in making the tool work to see ELLIPTICAL contours instead of CIRCULAR contours for a domain with thermal conductivity anisotropy.

  Reply With Quote


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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
How to import mesh from ICEMCFD to Fluent 6.2 jeevan kumar CFX 5 October 20, 2008 05:41
loading FLUENT 6.2 and GAMBIT on Red Hat LINUX Kiran FLUENT 1 October 16, 2007 09:12
Implementing own PDF in to fluent 6.2 and higher Paul FLUENT 0 August 6, 2007 10:47
FLUENT 6.2 manual lichun dong FLUENT 1 April 24, 2006 02:12
Info: Short Course On Thermal Design of Electronic Equipment Arnold Free Main CFD Forum 0 August 10, 1999 10:18

All times are GMT -4. The time now is 21:43.