# 2D simulation of a energy harvester

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 July 17, 2017, 23:43 2D simulation of a energy harvester #1 Member   Hanye Azimi Join Date: Oct 2016 Posts: 42 Rep Power: 9 Hi there I hope you are doing well. I'm going to simulate a flapping foil near water surface by openFoam. I mean plunge and pitch motion by flapping. Actullay this is an energy harvester like a turbine blade. In my case the foil rotates about 90 degree so I have to use RBF method for dynamic mesh, I suppose. Please, tell me what solver is the best for this case and how to set the folders (0, constant & system). Also I need to know how to produce a dynamic mesh in RBF method? Thanks in advance

August 27, 2017, 13:10
#2
Retired Super Moderator

Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,975
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Rep Power: 128
Greetings ronak,

You sent me a PM about 10 days before this post, but the question seems to be somewhat related. Quoting part of the message you had sent me:
Quote:
 Originally Posted by ronak I'm working on an flapping foil near water surface.I wish to have motion mesh without using dynamic mesh. I wonder if there is a way to move whole the domain together as the phase angle could be 90 and you know dynamic mesh goes in troube with angles which are not small. Do you have any information about this?
There are at least 3 ways you can do this:
1. If you don't want to use dynamic mesh specifically, then MRF or SRF modelling could be an interesting strategy.
• These models define that the "world is rotating" instead of the object itself, but the problem is likely that you would have an excess of waving going around the foil, since the fluid itself was rotating and not the foil, so it would become more of a mixing chamber than a foil flow simulation.
• Therefore I believe that MRF or SRF is out of the question.
2. Use AMI (OpenFOAM) or GGI (foam-extend) for defining a region in the mesh that separates the rotating region from the fixed region.
• Therefore your foil would be placed inside a cylinder and the mesh of this cylinder would rotate, while the AMI/GGI interface between cylinder and outside domain would do the calculations to transfer the flow between sides.
• It would still use dynamic meshing, but it would not require the whole mesh around the foil to bend.
• In foam-extend, you can find tutorials that use GGI by running this command:
Code:
`find \$FOAM_TUTORIALS -type f | xargs grep cyclicGgi`
• In OpenFOAM, by running this command:
Code:
`find \$FOAM_TUTORIALS -type f | xargs grep cyclicAMI`
• The tutorial case "incompressible/pimpleDyMFoam/wingMotion" comes to mind for the foil moving around, as it's in the list for Slerp here: https://openfoam.org/release/2-3-0/mesh-motion/
• As for using RBF in foam-extend, see the tutorial "incompressible/icoDyMFoam/movingBlockRBF"

Best regards,
Bruno
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 September 6, 2017, 02:46 #3 Member   Hanye Azimi Join Date: Oct 2016 Posts: 42 Rep Power: 9 thank you a lot

 Tags energy harvester, flapping foil, openfoam, rbf