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-   -   ANSYS/CFX, MFX FSI: piezoelectric microfluidic channel pumping problem (http://www.cfd-online.com/Forums/cfx/95289-ansys-cfx-mfx-fsi-piezoelectric-microfluidic-channel-pumping-problem.html)

 gogohusky December 12, 2011 13:44

ANSYS/CFX, MFX FSI: piezoelectric microfluidic channel pumping problem

Dear all:

I'd like to thank singer1812 and stumpy first for their comments to help me run the MFX example in ANSYS manual.

I am trying to analyze a fluidic pumping problem in vibrational channel with ANSYS 12.1.
The vibration of the channel is actuated by piezoelectric material, PZT, with pairs of electrodes operating at different frequencies or phase shift.
(The idea is similar to this example: http://www.astem.or.jp/kyotokesshu/r...09/a/21-10.pdf)

Initially I thought I'd need transient fluid-solid interaction with ANSYS/CFX MFX because of the different frequencies in PZT actuation and the presence of fluid. (Maybe you can comment on this.)
I have followed closely on the 'Example Simulation of a Piezoelectric Actuated Micro-Pump' in the coupled-field manual.
So far I have finished the PZT-actaution part, but got stuck with the MFX procedure.
I don't really know how to apply the changing voltage load at different time steps in MFX.
I've searched past posts and the Verfication manual, but still not know how to solve my problem.
Maybe more experience users can kindly help me with this.

The sinusoidal voltage load I use on PZT for the structure part is applied through a DO loop.

[Example code]-----------------------
!constant setup
pi=4*atan(1)
!Applied voltage
V=100
!Applied Frequency
Freq=20
!Time steps used in solution
Tstep=1/(20*Freq)
:
:

/SOLU
ANTYPE,TRANS
TINTP,,0.25,0.5,0.5

!The first time step is applied through a ramped load to make sure a convegent step happens.
TIME,Tstep
KBC,0
!Application of different voltages
Vapp1=V*(sin(2*pi*Freq*Tstep-2*pi/3))
Vapp2=V*(sin(2*pi*Freq*Tstep))
Vapp3=V*(sin(2*pi*Freq*Tstep+2*pi/3))
:
:(voltage application to specific nodes)
:
ALLSEL,ALL
SOLVE

!The following time steps are done in stepped load. Do loop ends at time=0.25 sec.
*DO,idxT,(2*Tstep),0.25,Tstep
TIME,idxT
KBC,1
Vapp1=V*(sin(2*pi*Freq*idxT-2*pi/3))
Vapp2=V*(sin(2*pi*Freq*idxT))
Vapp3=V*(sin(2*pi*Freq*idxT+2*pi/3))
:
:(voltage application to specific nodes)
:
ALLSEL,ALL
SOLVE
*ENDDO

FINISH
-----------------------------------------

I am really confused about applying different time steps in the MFX /SOLU process.
Maybe someone can explain it with a sample code?
Or is there other better way of applying the sinusoidal voltage?

Thank you all for your help!

Sincerely,

Ryan

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