[psd]

What is the best method to model a Darrieus-type vertical axis wind turbine in two dimensions? Basically there are three potential techniques I'm considering: streamtube models, vortex models and FEM. What are the advantages and disadvantages of each technique? Are there any streamtube or vortex codes around? I couldn't find any.

Thanks.

[harishg]

What do you exactly expect to get out of your modeling ? Depending on your requirement you can do anything between a panel method and a full LES.

[psd]

Ultimately, the goal would be to extract the information how much power does the turbine produce. So quantities of interest are the forces on the blades, torques etc.

What are panel method and LES?

[wei]

You can use CFX. Hope this helps a wee bit.

Dai, Y M and Lam, W, Numerical Study of Straight-bladed Darrieus-type Tidal Turbine; Proceedings of the Institution of Civil Engineers, Energy, 2009, 162, No. 2, 67-76.

[gocarts]

Originally Posted by psd

What are panel method...?

For a panel method description try:
http://www.symscape.com/blog/why_use_panel_method

For a vertical-axis wind turbine example (Lenz2 specifically) try:
http://www.symscape.com/node/662

Full disclosure: I present Symscape who develop and sell a panel method.

[psd]

Originally Posted by gocarts

For a panel method description try:
http://www.symscape.com/blog/why_use_panel_method

For a vertical-axis wind turbine example (Lenz2 specifically) try:
http://www.symscape.com/node/662

Panel method certainly seems like a good option for an inexperienced modeler. What are its main limitations for this kind of problem? It seems that lots of assumptions about flow conditions are made. Are there any additional resources for more insight on the subject?

It seems that streamtube and vortex methods are still the most used techniques for Darrieus modeling. I haven't found any codes implementing these though and any tips as where to find them would be greatly appreciated.

[gocarts]

Originally Posted by psd

It seems that lots of assumptions about flow conditions are made. Are there any additional resources for more insight on the subject?

An excellent discussion and description of panel methods is available in the book Low Speed Aerodynamics, from Katz and Plotkin.

[psd]

I have access to CFX, Fluent, Elmer and OpenFOAM. Some are based on finite element method and some on finite volume method. Which method suits the problem best? Are Elmer and OpenFOAM on par with Fluent, being open source and all?

Also, the Symscape package seems interesting. But why would one choose that instead of the abovementioned packages? What are its advantages?

[gocarts]

Get the marketing out of the way first

SymLab Professional is affordable ($300/yr, 50% discount for academic users), easy to learn and easy to use. It incorporates a panel method flow module.

Now for the meat:

A panel method solver is good for predicting lift and pressure drag (no skin friction) for fully attached airfoil flows away from stall (as you'll find for a Darrieus under steady running conditions). Panel methods only require a surface grid unlike finite-element/volume methods which require a volume grid - making panel methods easier to setup and faster in obtaining a solution.

Arbitrary rigid body motion (such as you'll find with a rotating wind turbine) is relatively easy to model in a panel method.

I see panel methods as complimentary to finite-element/volume methods. Panel methods are useful in the concept design phase of streamlined bodies as a precursor to committing to a more thorough and time consuming simulation accounting for viscosity.

Again, for more on the pros/cons of panel methods try http://www.symscape.com/blog/why_use_panel_method

OpenFOAM is on a par with FLUENT in terms of capabilities, at least for your application. However, OpenFOAM lacks an integrated GUI - this is about to change so watch this space: http://www.symscape.com/fourth-openf...-2009-abstract

Full Disclosure: I represet Symscape the developer of SymLab