2D moving cylinder-Mapping

5 Jun 2020

      *******************
This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. 
If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address.
*******************
Hi NEKTAR++ users,
I wonder if there is anyone could help me to converge my 2D simulations over a moving cylinder with high frequency. I've been stuck with this problem for two months.
Actually the case is exactly the same as CylFlow_Mov_mapping.xml case (attached here). I have only increased the vibration frequency (f) to 200 and reduced the amplitude (A) to 0.01. But it is not working at all. I have tried every possible option such as:

  1.  Using SpectralVanishingViscosity (DGKernel), DEALIASING, SPECTRALHPDEALIASING: Not helpful. I have tried all of the SVV options, but non of them helped me to converge the results.
  2.  Performing simulations at very low Re numbers and low P orders and then shifting to higher orders : Not helpful. It diverges even at Re=200 and P=4.
  3.  Using too small time steps (1e-7 or 1e-8): Not helpful. It diverges anyway.
  4.  Using low frequencies, such as f=2, 3 etc and then shifting gradually to higher frequencies: Not working. It diverges even at f=30 or lower values.
  5.  Usign HOutflow boundary conditions at the outflow: Not helpful in this study.

I would be grateful if someone has experience to resolve the divergence issue of this problem. (The initial conditions are set as default values in the code below.)
******************************
    <EXPANSIONS>
        <E COMPOSITE="C[73]" NUMMODES="5" TYPE="MODIFIED" FIELDS="u,v,p" />
    </EXPANSIONS>

    <CONDITIONS>
        <SOLVERINFO>
            <I PROPERTY="EQTYPE" VALUE="UnsteadyNavierStokes" />
            <I PROPERTY="SolverType" VALUE="VCSMapping" />
            <I PROPERTY="EvolutionOperator" VALUE="Nonlinear" />
            <I PROPERTY="Projection" VALUE="Galerkin" />
            <I PROPERTY="TimeIntegrationMethod" VALUE="IMEXOrder1" />
           <I PROPERTY="SpectralVanishingViscosity" VALUE="DGKernel" />
            <I PROPERTY="DEALIASING" VALUE="True"/>
            <I PROPERTY="SPECTRALHPDEALIASING" VALUE="True" />
        </SOLVERINFO>

        <PARAMETERS>
            <P> TimeStep      = 1e-7             </P>
            <P> NumSteps      = 100000000                </P>
            <P> IO_CheckSteps = 500                </P>
            <P> IO_InfoSteps  = 100               </P>
            <P> IO_CFLSteps  = 100                </P>
            <P> Re            = 200               </P>
            <P> Kinvis        = 1/Re              </P>
            <P> f             =  200            </P>
            <P> A             = 0.01              </P>
            <P> omega         = 2*PI*f               </P>
        </PARAMETERS>
        <VARIABLES>
            <V ID="0"> u </V>
            <V ID="1"> v </V>
            <V ID="2"> p </V>
        </VARIABLES>
        <BOUNDARYREGIONS>
            <B ID="0"> C[74] </B>      <!-- Wall -->
            <B ID="1"> C[76] </B>      <!-- Far Field -->
            <B ID="2"> C[77] </B>      <!-- Outflow -->
            <B ID="3"> C[75] </B>      <!-- Inflow -->
        </BOUNDARYREGIONS>
        <BOUNDARYCONDITIONS>
            <REGION REF="0">
                <D VAR="u" USERDEFINEDTYPE="MovingBody" VALUE="0" />
                <D VAR="v" USERDEFINEDTYPE="MovingBody" VALUE="0" />
                <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" />
            </REGION>
            <REGION REF="1">
                <D VAR="u" VALUE="1" />
                <D VAR="v" VALUE="0" />
                <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" />
            </REGION>
            <REGION REF="2">
                <N VAR="u" VALUE="0" />
                <N VAR="v" VALUE="0" />
                <D VAR="p" VALUE="0" />
            </REGION>
            <REGION REF="3">
                <D VAR="u" VALUE="1" />
                <D VAR="v" VALUE="0" />
                <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" />
            </REGION>
        </BOUNDARYCONDITIONS>

        <FUNCTION NAME="Mapping">
            <E VAR="x" VALUE="x" />
            <E VAR="y" VALUE="y+A*cos(omega*t)" />
        </FUNCTION>
        <FUNCTION NAME="MappingVel">
            <E VAR="vx" VALUE="0.0" />
            <E VAR="vy" VALUE="-1.0*omega*A*sin(omega*t)" />
        </FUNCTION>

        <FUNCTION NAME="InitialConditions">
            <E VAR="u" VALUE="1.0" />
            <E VAR="v" VALUE="0.1" />
            <E VAR="p" VALUE="0.0"/>
        </FUNCTION>
    </CONDITIONS>

    <MAPPING TYPE="Translation">
        <COORDS>Mapping</COORDS>
        <VEL>MappingVel</VEL>
        <TIMEDEPENDENT>True</TIMEDEPENDENT>
</MAPPING>
************************************

Many thanks
Mahdi
This message is intended solely for the addressee and may contain confidential and/or legally privileged information. Any use, disclosure or reproduction without the sender’s explicit consent is unauthorised and may be unlawful. If you have received this message in error, please notify Northumbria University immediately and permanently delete it. Any views or opinions expressed in this message are solely those of the author and do not necessarily represent those of the University. Northumbria University email is provided by Microsoft Office365 and is hosted within the EEA, although some information may be replicated globally for backup purposes. The University cannot guarantee that this message or any attachment is virus free or has not been intercepted and/or amended.

Mahdi Erfanian Nakhchi

Sherwin, Spencer J

tags

participants (2)