Dear all,
I am interested about studying the rotational cylinder in free flow (for
incompressible flow). Looking around the Nektar's manual I realized that
there is an option which, I think, allows to compute it, the MovingBody
along with the Mapping (10.6.3 - 10.6.5) from Nektar++'s manual v4.4.0.
I am using the example: the CylFlow_Mov_mapping as a reference one.
However, I can not completely understand how it works. (I took the
example from the 4.3.5 version)
First of all, that example is for a rotational cylinder or is it for a
cylinder moving up and down on a periodic motion?
Tanking into account the first option,
The mapping function computes the new coordinates for the specified
boundary, However, I do not understand why the function is specified in
that way:
<FUNCTION NAME="Mapping">
<E VAR="x" VALUE="x" />
<E VAR="y" VALUE="y+A*cos(omega*t)" />
</FUNCTION>
The value of the parameter A is not the radius of the cylinder, so it is
not deifying a rotation over its center. Also, the new /x/ coordinate is
the same as before, so the cylinder just moved upwards or downwards.
Secondly, what is the MappingVel functions used for? I think it is used
for specify the velocity on the new coordinates. However, the way it is
defined, I think, it does not define a new velocity coordinates.
What I am misleading?
A part from that, I would also compute the aerodynamic forces on the
moving surface, so I inserted the following:
<FORCE TYPE="MovingBody">
<PARAM NAME="OutputFile">DragLift.frc</PARAM>
<PARAM NAME="OutputFrequency">10</PARAM>
<PARAM NAME="Boundary"> B[0] </PARAM>
</FORCE>
and also:
<MAPPING TYPE="Translation">
<COORDS>MovingBody</COORDS>
<VEL>MappingVel</VEL>
</MAPPING>
However, the file DragLift.frc is not generated.
Hope I have well explained and clarified all my inquiries.
Thank you very much,
Guillermo Suarez.