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sandialabs / CACTUS

CACTUS (Code for Axial and Cross-flow TUrbine Simulation) is a turbine performance simulation code, based on a free wake vortex method, to study wind turbines and marine hydrokinetic (MHK) devices.
BSD 3-Clause "New" or "Revised" License
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CACTUS GUST SIMULATION #29

Closed sakibsadman7 closed 4 years ago

sakibsadman7 commented 4 years ago

Hi everyone,

I was wondering how do one correctly model the gust simulation correctly in CACTUS? I have played around with the igust, gustamp, gusttime, gustX0 parameters but I get no difference in the result. Would be grateful for some tips and suggestions!

Best Wishes, Sadman Sakib The University of Texas at Dallas

xflow-ian commented 4 years ago

I have also been having issues with the gust simulation. By monitoring the fieldDataoutput, I am able to observe that setting igust = 1 overrides the free stream to be uniform, even when slex is non zero. I have tried a variety of physically relvant values of gustamp, gusttime, and gustX0, but am not able to observe the gust in the free stream or induced velocity fields.

whophil commented 4 years ago

It looks like shear is ignored when igust = 1.

After some experimentation, I was able to see gust effects in the exported field data. Can you share the gust parameters you are using?

xflow-ian commented 4 years ago

Glad to hear it is working for you! My gust parameters were gustamp = 2, gusttime = 0.5, gustX0 = -5. The gust starting location, gustX0, was chosen to be upstream of the rotor and my gusttime corresponded to half a rotation of the turbine. The nominal free stream velocity was 8 m/s so I would have expected a 2 m/s gust to be noticeable.

For my field data, I was recording 20 points vertically spaced at the X-Z position 2 diameters upstream of the rotor.

xflow-ian commented 4 years ago

Could you share your parameters so I can try to recreate them on my machine?

whophil commented 4 years ago

I've attached a modified TestCase1/TestHAWT.in which applies a gust and also samples field data every timestep at the (0, 0, 0) using the Probe feature.

Here is a plot of Ufs/Uinf from the probe data.

image

TestCaseGust.zip Unzip this into [CACTUS source]/test/ to run.

xflow-ian commented 4 years ago

Thanks for sharing this example. I was able to replicate it on my machine. Additionally, I was able to change the gust parameters and have the gust profile change as expected.

whophil commented 4 years ago

Great! The confusing part for me was the gusttime parameter, which needed to be much longer than what I had originally set when I was just messing around. Closing this issue.