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QUESTION: Validation case study

Validation case study 2 years 6 months ago #1

  • harsh shah
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I worked on Flow past cylinder and calculated heat loss when flow pass through cylinder. I would like to ask that which results should i add for validation case study?
Actually, i calculated heat transfer rate theoretically and compare this value to simulation value by taking screenshot of TUI. Moreover, I show co-efficient of drag value graph and residual graph.
1)Do i need to add any other graph for validation case study?
2)What is the grid independency test and which values do we required for this?
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Validation case study 2 years 6 months ago #2

  • Praveen Kumar
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Comparison CFD results with analytical/theoretical values is sufficient for validation, if we don't have the experimental data.

Grid Independence Study is done to study the impact of mesh refinement on results. This is just to make sure, whether the solution is independent of grid i.e., no considerable changes in result will be seen even if refine the mesh further.
Read more:
Grid Independence Study
Praveen Kumar
LearnCAx
www.learncax.com
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Validation case study 2 years 6 months ago #3

  • wali
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Dear Shah,

Before performing any new research in CFD, validation is necessary either it is from numerical or experimental data but experimental data is highly recommended.
Since you are working for the flow past circular cylinder, therefore numerous work have already published in journals so it easier for your validation.
The following test should perform before any research in order to optimize the computational time.
1) Domain Independent Test.
2) Grid Independent Test.
3) Time step size test.
In this you compare your result with the published work, for this you can select the following parameter:
1) Drag Coefficient.
2) Lift Coefficient.
3) Nusselt No.
4) Strouhal Number.
The first three if you are working in the field of Heat transfer and Aerodynamic Characteristic while the last one for the vortex shedding characteristic which is also dependent to the frequency of lift force.

Regards
Wali
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The following user(s) said Thank You: Praveen Kumar

Validation case study 2 years 6 months ago #4

  • harsh shah
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Thx for reply.
I met to my professor.He told that only grid independence test is not enough for this cfd study. Of course it is a master thesis so what other values can i add?
1)i am planning to add drag graph.
2)heat transfer co efficient graph .
Now my question is,
1)what is the difference between surface heat transfer HTC and WALL HTC in fluent?because surface heat transfer rate is match with theoretical calculation but wall htc value is much higher then theoretical values.
2)If i want to show that at theta angle,htc value is decrease and then with increase theta,htc value is increase. So how can i show it in fluent? please write down step by step procedure to get theta value. Because i want to make graph of theta vs. htc value.
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