Innovation & Quality

We would like to congratulate Putra Adnan Fadilah on winning the NUMECA White Paper Contest 2017. Putra analyzed the effect of mesh-screens in wind-tunnels to reduce flow-separation. For his work, we have awarded him a cash prize of 500 euros and invited him to present his work in the NUMECA User Meeting.

Mesh-screens are used in the wide-angle-diffusers (WAD) of wind-tunnels with the intention to reduce the flow-separation phenomena. Putra studied the effect of four types of mesh-screens placed at the inlet, mid-section and outlet of the WAD.

  • As the microscale modelling of the mesh-screens would be computationally expensive, they were macroscopically modelled as porous media.
  • Based on Idelick [*]’s handbook of hydraulic resistance, the K’ coefficient of the porous-medium was determined based on the properties of the mesh-screen (such as thickness of the screen, perforation-size), reynolds-number and the expected pressure-drop across the screen.
  • After generating the CFD-mesh with HEXPRESS™, Putra performed multi-domain steady simulations for the 4 types of screen-meshes with the FINE™/Open solver using the previously determined K’ coefficient.
  • He observed that the screen with the higher-wire-diameter (lowest porosity) exhibited the lowest flow-separation.
  • With further investigation, he was able to conclude that the flow-separation can be eliminated by using three screens of the lowest porosity.

The flow separates when the wind tunnel does not have mesh-screens


The separation of flow is stopped with the use of mesh screens (porosity 0.69) in the wind tunnel


Once again, we would like to congratulate Putra as he was still a student when he made the entry. If you are a student and would like to use NUMECA software, have a look at our free-student-offer. For any special academic requests please write to us at


[*] E. Idelchik, I. (1987), Handbook of Hydraulic Resistance, 2nd Edition. Hemisphere Publishing Corporation, New York NY.


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Colinda Francke

Colinda holds a Master of science in Aerospace Engineering from TU Delft. She also followed the diploma course at Von Karman Institute. Since 2001, she works at NUMECA International. For the first 11 years, she worked as in the technical support department. Today she is responsible for academic use, documentation and EN 9100 Quality Management.


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