Computational Fluid Dynamics Page

The Computational Fluid Dynamics (CFD) research group, under the direction of Professor Yassin Hassan, seeks to utilize and develop industrial CFD codes for the purpose of performing research within the Nuclear Engineering field, as well as other related fields.  The group uses both American and international codes in this pursuit.  In the recent past, the group has used the codes CFD-ACE, CFX, GUSTCC, STAR-CD, and TRIO.

Much of the recent work done in this group has involved the use of Large Eddy Simulation to simulate transient turbulent flows.  The Nuclear Engineering industry has become very interested in these flows due to cracking in the tubes of steam generators at many nuclear power plants.  As water enters the steam generator, it impinges transversely on the tubes causing vibration.  Over time, this vibration can cause the tubes to crack.  Animations of turbulent flow around a single cylinder and a tube bundle are shown below:

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Turbulent Flow in a Tube Bundle Using GustCC

This is an 8 second AVI movie showing vorticity formation around a tube bundle using Large Eddy Simulation. (~ 1.6 Mb)

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Turbulent Flow Around a Cylinder Using GustCC

This is a 20 second AVI movie showing the velocity field around a single tube in a channel, also using Large Eddy Simulation. ( ~ 3.1 Mb)

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Current work in our group involves the use of TRIO (a French code developed by CEA) to study thermal cycling in reactor cold legs.  Several plants have had problems with pipe cracking due to thermal cycling.  If hot water leaks in to the cold leg, the mixture of the two flows will cause a cycling temperature near the hot water inlet, and over time this temperature cycling can cause enough strain on the pipe to cause cracking.  Due to the inherently transient nature of this phenomenon, we feel that Large Eddy Simulation is the best tool to accurately generate solutions.

An example of a transient flow, as calculated by TRIO is shown below:

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Flow Around a Square Obstacle Using TRIO

This is a 10 second AVI movie showing the z-vorticity for a 2D calculation of vorticity, ignoring both turbulence and diffusion, around a square obstacle in a channel. ( ~ 700 Kb)

This is a 5 second AVI movie showing the z-vorticity for a 3D calculation of vorticity around a square obstacle using Large Eddy Simulation with the Dynamic Smagorinsky Subgrid Scale Model. ( ~ 700 Kb)

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If you have questions or comments, or would like more information concerning the material discussed here, please contact either Dr. Yassin Hassan (hassan@cedar.tamu.edu) or Mr. Donald Helton (dmhelton@cedar.tamu.edu).

Last Updated on 02/05/01

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