[Nek5000-users] angular velocity to the mesh velocity

Fri Feb 9 08:36:39 CST 2018

Thank you for your replay Marco. 

I will explain from the begening clearly. My current task is to validate Fluid structre interaction on aero foil(NACA profile). The equations which i have to solve I have attached for aero foil. Before this case, I had succesfully done a case of vortex induced vibration of cylinder in NEK5000. And the code below shows a part of the forced oscillating cylinder. From this code I learned that the body motion prescribed through the mesh velocities but I also think that I can only give translational velocity components in NEK5000 to presribe a body motion (mesh as well). 

Since my aero foil has pitching (it rotates up and down about an axis at angle theta). Since it has to be a FSI problem my plan is by using " call torque_calc(scale,x0,.true.,.true.)" I will get the M (moment about the elastic axis (x0)) and it gives as an input to the Equation of angular motion (attached with this email). Then using Range Kutta method I get the angular velocity of the profile (r, theta,z co ordinates). Then I am planning to conver this angular velocity into linear velocity components (x, y, z direction) then impose into the wx,wy,wz components and I hope it leads to the movement of mesh thus the geometry. 

My question is could you think that its possible? Or is there any other simple way to give this angular velocity to my NACA profile about the elastic axis (x0)? And I feel difficulty to convert the angular velocity into linear velocty and gives its to each nodes which is on "mv" B.C . 
Could you please help me with this situation by an example if you have. 

Thanks in advance 

c Cylinder velocity components 

ucx = 0.0 
ucy = amplitude * omega * cos(omega*time) 
ucz = 0.0 

n = nx1*ny1*nz1*nelv 
do i=1,n ! Translational velocity 
wx(i,1,1,1) = basev(i)*ucx ! component. 
wy(i,1,1,1) = basev(i)*ucy 
wz(i,1,1,1) = basev(i)*ucz 

umeshx(i,1,1,1) = wx(i,1,1,1) 
umeshy(i,1,1,1) = wy(i,1,1,1) 
umeshz(i,1,1,1) = wz(i,1,1,1) 

enddo 

De: "nek5000-users" <nek5000-users at lists.mcs.anl.gov> 
À: "nek5000-users" <Nek5000-users at lists.mcs.anl.gov> 
Envoyé: Vendredi 9 Février 2018 15:03:26 
Objet: Re: [Nek5000-users] angular velocity to the mesh velocity 

Sijo, 

The mv_cyl example is a 2-D moving body example. As for the mesh velocity, can you please be more specific? 

Marco 

From: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov> on behalf of "nek5000-users at lists.mcs.anl.gov" <Nek5000-users at lists.mcs.anl.gov> 
Reply-To: "nek5000-users at lists.mcs.anl.gov" <Nek5000-users at lists.mcs.anl.gov> 
Date: Friday, February 9, 2018 at 8:56 AM 
To: nek5000-users <Nek5000-users at lists.mcs.anl.gov> 
Subject: [Nek5000-users] angular velocity to the mesh velocity 

Hi Neks, 

Its a long time that i came up with something. So here we go, 

SInce I was doinf the FSI of aero foil, I have to deal with 2 degrees of freedom (its a 2D case) one in vertical and another in angular direction about the elastic axis of the profile. I could code the vertical motion of the foil but before starting the angular motion I have some doubts. Is there anyway to give the angular velocities directly to the mesh velocities? Apart from the translational velocity components Or Do you want me to covert the angluar velocities into translational components and give to mesh velocities? Do you have any example with a body which is rotating? 

Thanks in advance 

Sijo GEORGE 

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