Velocity Different due to Interface

KindaHungry · November 22, 2018, 05:12

Hi good day Everyone

,

I have created an in-place internal interface to separate rotating and static region for simulating open water test. When I open a scalar scene for axial velocity, i found that the axial velocity in the interface is much lower than outside the interface but I have actually assigned to both interface and inlet the same velocity.

So is it possible to make both of them same velocity by maintaining the interface?
Is it any step that I have done wrong when creating the interface causing the velocity difference?

Quite urgent please help me

taxalian · November 22, 2018, 14:54

Hi, is the solution converged and how many iterations you run the simulation? plz show the velocity vectors plot and make sure that the you properly define the rotating frame of reference.
Regarding the interface make sure that the interface between rotating and static region is well defined, reasonable mesh density in the interface area might improve the convergence.

KindaHungry · November 22, 2018, 22:26

Hi! I use 600 iteration for each advanced ratio and total 6600 iteration for J=0.0 to J=1.0. What is meant by defined properly ya? I created new rotating reference frame in Tools and then set the Motion Specification of the Rotating Region into Rotating.
For the interface, I have created 2 interfaces, one under static region, another one under rotating region.
For mesh inside the interface, I used size of 0.0045m; outside the interface 0.045m.

taxalian · November 23, 2018, 02:20

ok fine, then i would suggest just to check the blade rotation clockwise/anti-clockwise. The number of iterations won't tell you anything make sure that the solution converged for each advance ratio. This means that you can do for example in your case the reporting and monitoring for one of the desired variable like thrust/torque coefficient. Hope this helps good luck.

KindaHungry · November 25, 2018, 04:04

Hi! Taxalian, thanks for the suggestion. I will give it a try first! Thank you very muchhh!

me3840 · November 25, 2018, 20:04

Your issue is probably related to the fact that either (a) your spinning and nonspinning regions do not share an axis setting or (b) there's an issue with your reference frame. If axial velocity is cast in the relative frame then you might get your image.

November 23, 2018, 02:20		#4
taxalian Senior Member Join Date: Nov 2010 Posts: 139 Rep Power: 15	ok fine, then i would suggest just to check the blade rotation clockwise/anti-clockwise. The number of iterations won't tell you anything make sure that the solution converged for each advance ratio. This means that you can do for example in your case the reporting and monitoring for one of the desired variable like thrust/torque coefficient. Hope this helps good luck. KindaHungry likes this.

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November 22, 2018, 14:54		#2
taxalian Senior Member Join Date: Nov 2010 Posts: 139 Rep Power: 15	Hi, is the solution converged and how many iterations you run the simulation? plz show the velocity vectors plot and make sure that the you properly define the rotating frame of reference. Regarding the interface make sure that the interface between rotating and static region is well defined, reasonable mesh density in the interface area might improve the convergence.

November 22, 2018, 22:26		#3
KindaHungry New Member Join Date: Jun 2018 Location: Malaysia Posts: 16 Rep Power: 7	Hi! I use 600 iteration for each advanced ratio and total 6600 iteration for J=0.0 to J=1.0. What is meant by defined properly ya? I created new rotating reference frame in Tools and then set the Motion Specification of the Rotating Region into Rotating. For the interface, I have created 2 interfaces, one under static region, another one under rotating region. For mesh inside the interface, I used size of 0.0045m; outside the interface 0.045m.

November 25, 2018, 04:04		#5
KindaHungry New Member Join Date: Jun 2018 Location: Malaysia Posts: 16 Rep Power: 7	Hi! Taxalian, thanks for the suggestion. I will give it a try first! Thank you very muchhh!

November 25, 2018, 20:04		#6
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	Your issue is probably related to the fact that either (a) your spinning and nonspinning regions do not share an axis setting or (b) there's an issue with your reference frame. If axial velocity is cast in the relative frame then you might get your image.