Wrong figure in Hrv. thesis?

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April 6, 2013, 03:05
Wrong figure in Hrv. thesis?
#1
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Santiago Marquez Damian
Join Date: Aug 2009
Location: Santa Fe, Santa Fe, Argentina
Posts: 418
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Hi there, a few days ago Dr. Axel Larreteguy told me about some concerns about Figure 3.7 in Hrv. thesis (see attachment). Here we have the vectors and , which have units of area and then vector , the correction, which seems to take in account the displacement of from the face centroid , so that it has units of distance. The concerns are:

1. Why the differences in units?
2. Do the vector decomposition make sense as is drawn?

Below the figure it is stated that vector is not used

3. The correction vector is not used because simplification or because it is zero (I guess so)?

Following the work of Mathur and Murthy

http://www.tandfonline.com/doi/abs/1...915105#preview

it leads to a zero correction. If it is the wrong interpretation

4. How do we interpret the figure?

Attached Images
 NonOrthBound.jpg (25.7 KB, 14 views)
__________________
Santiago MÁRQUEZ DAMIÁN, Ph.D.
Post-doctoral Fellow
Research Center for Computational Mechanics (CIMEC) - CONICET/FICH-UNL
T.E.: 54-342-4511594 Ext. 1005
Güemes 3450 - (3000) Santa Fe
Santa Fe - Argentina
http://www.cimec.org.ar

April 6, 2013, 14:53
#2
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Philip Cardiff
Join Date: Mar 2009
Location: Dublin,Ireland
Posts: 570
Rep Power: 19
Quote:
 Originally Posted by santiagomarquezd Hi there, a few days ago Dr. Axel Larreteguy told me about some concerns about Figure 3.7 in Hrv. thesis (see attachment). Here we have the vectors and , which have units of area and then vector , the correction, which seems to take in account the displacement of from the face centroid , so that it has units of distance. The concerns are: 1. Why the differences in units? 2. Do the vector decomposition make sense as is drawn? Below the figure it is stated that vector is not used 3. The correction vector is not used because simplification or because it is zero (I guess so)? Following the work of Mathur and Murthy http://www.tandfonline.com/doi/abs/1...915105#preview it leads to a zero correction. If it is the wrong interpretation 4. How do we interpret the figure? Thanks in advance,
Hi,

In Hrv's thesis (and in OpenFOAM), non-orthogonal correction is not employed on the boundary. This assumption is fine if we assume that phi does not vary along the boundary.
Although, if we assume that phi varies linearly along the boundary then non-orthgonal correction is required to maintain accuracy, as outlined in
E. De Villiers thesis (Fig. 4.7).

I believe that this correction is not performed in OpenFOAM because it may lead to mass flux across walls.

But boundary non-orthogonal correction can be employed through use of custom boundary conditions, such as fixedDisplacement (corrected version of fixedValue) in the solidMechanics branch of OpenFOAM-1.6-ext.

Hope it helped,
Philip

 April 7, 2013, 01:37 #3 Senior Member     Santiago Marquez Damian Join Date: Aug 2009 Location: Santa Fe, Santa Fe, Argentina Posts: 418 Rep Power: 15 Thanks Philip, it helped! I'm going to elaborate some ideas to post. Regards. __________________ Santiago MÁRQUEZ DAMIÁN, Ph.D. Post-doctoral Fellow Research Center for Computational Mechanics (CIMEC) - CONICET/FICH-UNL T.E.: 54-342-4511594 Ext. 1005 Güemes 3450 - (3000) Santa Fe Santa Fe - Argentina http://www.cimec.org.ar

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