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Old   April 7, 2012, 09:30
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Good morning.

Iím new to CFD softwares and it's theory. Searching on google I created some doubts. My intentions on CFD are external flows around wings and fuselages, extracting from the simulations the Cd and Cl of 2D and 3D geometries.

My doubts:
1- The precision of CFD method against experimental ones ?
2- Ansys (fluente/CFX) precision vs Solid Works flow ?
3- Possibilities of exporting geometry from a 64 bits CAD software to Ansys 32 bits (12) ?
4- On hardware is the processor more important than the RAM memory ?

Thanks
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Old   April 7, 2012, 23:36
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sheth roh
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Quote:
Originally Posted by leo_NM View Post
Good morning.

Iím new to CFD softwares and it's theory. Searching on google I created some doubts. My intentions on CFD are external flows around wings and fuselages, extracting from the simulations the Cd and Cl of 2D and 3D geometries.

My doubts:
1- The precision of CFD method against experimental ones ?
2- Ansys (fluente/CFX) precision vs Solid Works flow ?
3- Possibilities of exporting geometry from a 64 bits CAD software to Ansys 32 bits (12) ?
4- On hardware is the processor more important than the RAM memory ?

Thanks
Hi welcome to the forum.

I can answer the 1st and 2nd doubt that you have.

The precision depends on many things like mesh quality. The turbulence model you chose for simulating flow, and solution method taken to solve i.e higher order and lower order.

A good mesh along with suitable turbulence model and higher order solution methods can give wonderful results. I cant say that its 100% accurate but it can really be a robust tool for preliminary prediction of flow. Even the wind tunnel has many errors, you may have the wall effects and human errors in operating the wind tunnel. So, CFD is a tool for preliminary flow field prediction and then when changes are made in design only final model is checked in wind tunnel which can reduce the cost of design and optimization. If accuracy is not very important some people also do not conduct wind tunnel test they conduct designing and optimization only using CFD.

2. In my opinion for external flow, CFX and FLUENT are great. No idea about internal flow.


Hope this helps.

Regards
Sheth
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Old   April 8, 2012, 17:32
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John Chawner
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Hi leo_NM:

1. The relative accuracy of CFD versus experiment is an ongoing issue. Bottom line, you can get very accurate results using CFD for external flow around wings and fuselages. As a point of reference, search for "drag prediction workshop."

2. Not to be mean or anything, but I think you'll find Fluent and CFX to be more high fidelity than SolidWorks Simulation.

3. Exporting from 64-bit CAD to 32-bit CFD happens all the time. It should not be a problem.

4. Both processor and RAM are important. More RAM might give you more bang for your buck as they say.

Welcome to the world of CFD! Good luck.
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