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Virtual Wind Tunnel Testing: What To Use?

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Hey all, I'm working on a project that deals with aerodynamics and vehicles, and I'm not sure how to go about this. I've read a few books on the subject, and I understand most of it, but as for actual testing I'm not sure what direction to head in. I have access to Solidworks 2008, and Alias StudioTools 13, and also probably Rhino.

 

Let me know!

 

Thanks!

 

- Rob

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Do you have the Cosmosworks package for Solidworks? Thats the only tool that will let you do any kind of FEA out of what you listed.

 

I've played with it a bit, and frankly it's all a bit heavy. Setting up the simulation is one thing, but actually analyzing and making informed judgements from the results is another thing. Might be a good time to make friends with some Aero engineers.

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Do you have the Cosmosworks package for Solidworks? Thats the only tool that will let you do any kind of FEA out of what you listed.

 

I've played with it a bit, and frankly it's all a bit heavy. Setting up the simulation is one thing, but actually analyzing and making informed judgements from the results is another thing. Might be a good time to make friends with some Aero engineers.

 

 

Yeah, I started playing with CosmosFlow Express. I can get some sort of simulation to happen, but it isn't making much sense to me, nor does it look that cool nor can you save it as an animation.

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Guest kaiza

From my experience with Express for force analysis, it skips over a lot of options that are quite important - better to use the full CosmosFlow package.

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Are you actually planning to do the analysis or are you just after the smoke trails? If it is the first, you are going to struggle unless you have a background in fluid mechanics, and even then you need access to the kit (read wind tunnel). Its one thing sticking a model into a simulation software or wind tunnel - it's quite another being able to interpret the results.

 

If on the other had you are just after pretty pictures then you can easily fake it in pretty much any animation of rendering system. Just draw the smoke paths and use particle effects to simulate the smoke, or for a really quick cheat, turn the path into a tube and apply a neon type material to it (one with transparency fading to the outside).

 

Or of course, if you can hold of HyperDrive stick your model into that.

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Guest mcgreg

If you're dealing with aerodynamics, and have access to SolidWorks 2008, then Flow Simulation is your choice! If you have access to the educational edition, then you have access to Flow. If you only have access to the commercial package, then you don't have Flow Simulation... it's the way it is...

 

Flow Simulation is quite easy to use due to it's Wizard interface, and comes with some good tutorials. If you look inside the installation folder, there are also some PDF's which give a good insight on validation examples and some advanced boundary conditions parameters, specially regarding the mesh, which is of the utmost importance on FEA software.

 

Very powerful, very easy!!

 

Regarding FlowXpress, it has several limitations, as you might have seen by now. It only allows internal analysis (closed volumes) with air or water (ideal fluids), one inlet and one outlet. you can always create your wind tunnel assembly consisting of a cylinder, and place your model inside it. It can give you a good approximation, but with some associated error, because there's no mesh control (similar to SimulationXpress).

 

ps: just seen that last update was in february... non the less, it's written so...

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Guest Bowl of Soup

Short answer: Built-in apps for rapid, qualitative work without turbulence (like air-conditioning duct optimization), Fluent or CFX for anything turbulent (aka race cars, aircraft) or quantitative.

 

Depends on what analysis your interested in... Mesh design/control is half the battle, controlling your finite grid to maximize visibility into areas of interest is key, otherwise you may miss something because your grid was not fine enough at the right place. You get to control your mesh in better apps like Fluent and ANSYS CFX. Also if you are doing anything involving turbulence, look into these apps because with something like cosmos, you can only time-average your turbulence (limited algorithms). The results for turbulence are always way off in something like cosmos, and do not consider secondary flows (you need reynolds-averaging other such algorithms for turbulence).

 

 

At a certain level of analysis you need to start understanding the numerical algorithms, some are adequate for some conditions, some are not. Built-in apps like cosmos have limited algorithm sets and little mesh control. In my experience cosmos can give results ORDERS OF MAGNITUDE off, so a company may use results qualitatively (like how to reduce form drag, etc). I have seen the built-in analysis in NX4 and Pro-E also used qualitatively. Quantitative, I would go with CFX or Fluent, depending on what your academic (please tell me you have access to the licenses already, they are EXPENSIVE) organization uses.

 

If you are doing quantitative biomedical stuff, or anything using materials with visco-elastic behaviour, look into specialised apps written for research like ADINA.

 

Regards,

 

Don't forget a real Wind Tunnel with transducers and CNC wire-cut foam may be cheaper!!

 

BoS

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