# Simulation of rotating undershot water wheel

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 April 22, 2015, 23:00 #21 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,327 Rep Power: 138 There are several problems with the mesh you show: * I assume you want to model the river with a free surface. In that case you need to mesh a region of air above the river level as well. * You do not mesh the impeller. This is such a common mistake recently that it would be good if somebody wrote an FAQ about it. * You model the fluid region around the impeller with the impeller as a cut out region inside the domain. have a look at how the rotating machinery is modelled in the tutorials. * You put the domain around the impeller in a cylindrical domain and set it to be a rotating frame of reference, and connect this domain to the surroundings with a GGI interface

April 24, 2015, 02:57
#22
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Miss Anna
Join Date: Jan 2015
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Rep Power: 10
Thank you very much for your comment.
I have made new setup for this simulation by considering your comment. But, this time i use boolean operation to eliminate the water wheel structure. Besides that, I have include the air domain in the analysis to take account the air region in the river. Is it correct if I just eliminate the water wheel just like the picture attached. How can I apply the rotating frame of reference here?
Attached Images
 prtscrn 2.jpg (45.9 KB, 23 views) prtscrn 3.jpg (49.6 KB, 23 views)

 April 24, 2015, 05:50 #23 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,327 Rep Power: 138 As a rotating frame of reference domain should be cylindrical, you will need to put the impeller in a cylindrical cut out region. You then connect the stationary outer domain to the cylindrical inner domain with a GGI with a frame change condition.

April 26, 2015, 12:59
#24
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Miss Anna
Join Date: Jan 2015
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Oh I see. So, I have to make a rotating domain in the form of cylindrical right?

I have improved my setup based on your comment. But, when I runned the simulation, it produced no result. I have keep searching where the possible cause of the error. But, I still have no idea why it happened.
Do you have any idea of this problem?

Thank you.
Attached Images
 prtscrn 4.jpg (44.9 KB, 21 views) prtscrn 5.jpg (44.9 KB, 18 views) prtscrn 6.jpg (43.6 KB, 18 views)

 April 26, 2015, 19:35 #25 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,327 Rep Power: 138 The error message is very clear - it failed to interpolate an initial condition onto this mesh. Miss Anna likes this.

June 7, 2016, 23:24
Simulation of rotating undershot waterwheel
#26
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Join Date: May 2016
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Hi Everyone.

I am also working on simulation of water wheel in open channel flow. I am using Ansys CFX and using multiphase model which includes water and air as the working fluid.

I setting different inlet for both fluid. For water inlet, I set the velocity 0.03 m/s while for air inlet, I set the velocity to 0 m/s.

For outlet, I set the BC to static pressure with 0 relative pressure.
I attached the figure of my result here.

I am confusing why the water volume fraction is becoming like this. I dont have idea why the flow of water are becoming like this especially at the outlet.

And, Is it possible for the torque to be negative?

Thank you. Best regards.
Attached Images
 volume fraction.jpg (73.9 KB, 20 views) torque.jpg (75.0 KB, 15 views)

 Tags ansys cfx14, water wheel