Calculating Time Integral of Torque

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Hi everyone!

I am working on optimization of a Vertical Axis Wind Turbine by means of CFD simulation. I have been able to run my model and plot the torque exerted on the blades of the rotor by using a Time Dependent Study (see Figure 1 attached). Next thing I want to do is to compute the average torque over an interval of time so I can calculate de power coefficient of my wind turbine. I have tried to do this by integrating the Torque variable with respect to time using some built-in operators named timeint and timeavg but then my model just take too long to do this calculations and actually it never ends. Does anyone know a better way to do this or know what is my mistake?. I attached some screenshots of my way of getting the Torque values.

Greetings.



3 Replies Last Post Nov 18, 2020, 3:57 PM EST

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Posted: 1 month ago Oct 27, 2020, 2:47 AM EDT

You can use 'with' operator for this. This will give you what you want.

Hope that helps.

You can use 'with' operator for this. This will give you what you want. Hope that helps.

Edgar J. Kaiser Certified Consultant

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Posted: 1 month ago Oct 27, 2020, 5:06 AM EDT
Updated: 1 month ago Oct 27, 2020, 5:12 AM EDT

Eddy,

it is my experience too, that complex postprocessing can be very time consuming. My workaround in some cases is to shift those operations into the solver. The solvers are implemented much more efficient than the post processing. Check this blog contribution by Walter Frei to get some ideas: https://www.comsol.de/blogs/using-the-previous-solution-operator-in-transient-modeling/ Of course you need to modify this according to your needs. Your integrations would then run in additional ODEs making use of the previous solution.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Eddy, it is my experience too, that complex postprocessing can be very time consuming. My workaround in some cases is to shift those operations into the solver. The solvers are implemented much more efficient than the post processing. Check this blog contribution by Walter Frei to get some ideas: https://www.comsol.de/blogs/using-the-previous-solution-operator-in-transient-modeling/ Of course you need to modify this according to your needs. Your integrations would then run in additional ODEs making use of the previous solution. Cheers Edgar

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Posted: 1 week ago Nov 18, 2020, 3:57 PM EST

Hello.

I have a similar problem, where I would like to calculate the rms (average fluctuating velocity) in my model. I am solving a laminar system but there is "chaotic mixing", so I would like to get an average velocity field () and a rms field (). I was able to get the average velocity field by creating a time average dataset (in postprocessing), but have not been able to get the rms field.

Any help would be greatly appreciated. Thanks

Hello. I have a similar problem, where I would like to calculate the rms (average fluctuating velocity) in my model. I am solving a laminar system but there is "chaotic mixing", so I would like to get an average velocity field (\bar{U}(x,y)) and a rms field (u_{rms}(x,y) = \sqrt{(u^\prime - \bar{U})^2}). I was able to get the average velocity field by creating a time average dataset (in postprocessing), but have not been able to get the rms field. Any help would be greatly appreciated. Thanks

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