iMechanica - Fluid - Comments

Structure Fluid Interaction

luciano demasi — Fri, 07 Nov 2008 21:57:20 -0500

The interaction between structure and aerodynamics is very difficult. I worked in the area too. Without expressing here all the details (see the links at the end of this message), I can post here the main concepts.

1) The aerodynamics is considered linear and the effects of the viscosity are not considered.

2) The flow is assumed attached and subsonic. The compressibility can be included.

3) The structure is a collection of Finite Element plates in the space that simulate a possible equivalent plate model for a planar or non-planar wing system. The structure is geometrically nonlinear.

4) The structure takes into account the nonlinearities which can be important even if the deflections are not large. As an example, you can consider a Joined Wing configuration which, in general, is characterized by strong in-plane forces which affect the geometric stiffness matrix. The fact that the deflections are not very large allows one to use linear aerodynamics and assume that there is no separation of the boundary layer

5) Under the above mentioned conditions, the projections of the structural nodes on the reference configuration with no angle of attack can be considered constant. This simplifies the splining a lot because all the matrices used to transfer the aerodynamic loads from the aerodynamic mesh to the structural mesh are constant even if the structure deforms.

6) We are talking about panel codes, so vortex lattice for the steady case (see the book Katz J., and Plotkin A., "Low-Speed Aerodynamics - Second Edition,"
Cambridge University Press, NY, 2001) and Doublet Lattice for the unsteady case (Rodden W. P., Taylor P. F., McIntosh Jr S. C., "Further Refinement of the Subsonic Soublet-Lattice Method", Journal of Aircraft Vol. 35, No. 5, SEptember-October 1998)

7) For the steady case: the vortex lattice calculates the aerodynamic influence coefficient matrix and after some transformation an aerodynamic tangent matrix (referred to the structural mesh) is calculated. The aerodynamic tangent matrix is then added to the structural tangent matrix to obtain the aeroelastic tangent matrix. As you calculate the buckling load of a "pure" structure you can then calculate the divergence speed by gradually increasing the aerodynamic speed until the aeroelastic tangent matrix becomes singular

8) The unsteady case is more complicated. The main idea is to work with a set of reduced frequencies to get tabulated values for the generalized aerodynamic matrix. Then, Roger procudure can be used. After some other derivations, you move from the frequency domain to the Laplace domain and finally to the time domain. At this point you can numerically integrate the equation using Newmark method. The aerodynamic loads and lag effects affects the response of the system. This procedure is capable of capturing LCO when this is developed from structural nonlinearities (see the work of Attar, Dowell and White "Modeling of a Delta Wing Limit-Cycle Oscillations Using a High-Fidelity Structural Model", Journal of Aircraft Vol. 42, No. 5, September-October 2005)

You can see some details in the following conference articles:

Demasi L., Livne E., “
Aeroelastic Coupling of Geometrically Nonlinear Structures and Linear Unsteady
Aerodynamics: Two Formulations ”, Presented at the 49th
AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics & Materials
Conference, Schaumburg, Illinois, 7-10 April 2008

Demasi L., Livne E., “
Dynamic Aeroelasticity of Coupling Full Order Geometrically Nonlinear Structurs
and Full Order Linear Unsteady Aerodynamic - The Joined Wing Case ”,
Presented at the 49th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics
& Materials Conference, Schaumburg, Illinois, 7-10 April 2008

You can download the PDFs here:

http://attila.sdsu.edu/~demasi/articles/AIAA-2008-1758-644.pdf

http://attila.sdsu.edu/~demasi/articles/AIAA-2008-1818-885.pdf

http://attila.sdsu.edu/~demasi/default.htm

I feel your points are interesting.

Charlie.liang — Thu, 16 Oct 2008 17:47:18 -0400

I will try to contact you.

Re:

CAEengineer — Wed, 15 Oct 2008 12:11:00 -0400

http://www.comsol.fr/showroom/animations/361/

***********************************
CAE Engineer in Automotive Industry

Thanks for sharing.I found the following interesting animation.

CAEengineer — Wed, 15 Oct 2008 11:59:03 -0400

====================

some examples

abouziar — Wed, 15 Oct 2008 04:53:48 -0400

Hi CAEengineer

you coud take some results from our ftp server

server : ftp.unn.ru

password: mech-f.ex.

file examples.txt is with the discription of ccf.zip with some problems to demonstrate the method

capabilities for CFD, CSD and FSI

if any questions

e-mail abouziar@dk.mech.unn.ru

or we could disscus in in skype

best wishes

abouziar

Could you share some of your results?

CAEengineer — Tue, 14 Oct 2008 14:27:19 -0400

====================

FSI with Riemann's solver

abouziar — Tue, 14 Oct 2008 06:33:18 -0400

In my case (explicit 2D) FSI is not a problem, I came to CSD and FSI

from CFD (High order Godunov in moving Euler grid)

I use finite volume (high order Godunov method) for both:

Computational Fluid Dynamics and
Computational Solid Mechanics.

For the border Fluid-Structure I made an exact Riemann's solver.

For the Fluid Tate state eq. is used.

For the Solids (elastic case) - Hook's law,

there is an exact solution of this problem,

R.P. solver on the border- the same contact velocity of Fluid and Solids,

normal stress is equal to -pressure of fluid,

tangent stress = friction fluid-solids.

Each step the border is moved in acodernce with the velocity of this R.P. solver,

for 2D explicit case everything is simple:

body fitted mesh is constructed after moving FSI boundaries,

Fluid and Solids are integrated as in 2D moving Euler.

For for solids predictor step is linear (hook's law), all physics (plasticity, viscoplasticity and etc.

) is introduced in corrector step (splitting technics like for Fluids, it is enough

for 2 order)

For solids were problems with the big numerical viscosity from the border cells

(not enough accuracy on the border with free or pressure boundaries and so radiation

of the energy).

Now it works well from impacts time (km/sec) up to milionns steps (vibration

of constructions) . This border viscosity from free or pressure boundary is too big,

but it is possible to correct this viscosity using modified equation for these border cells,

up to the accuracy of the scheme (2 order)

after that moving Euler for solids became without any viscocity

(similar or even better than Wilkins in lagranzian).

It works well for the impact and explosion FSI problems

from the FSI up to vibration of construction (milions explicit steps).

So practically the same scheme for Fluids, Solids and FSI and it can be extended

like usual finte volume on different physics.

For 3D explicit case FSI is the same - simple (exact Riemann's solver).

Problem is how to integrate Solids in 3D in moving Euler for body fitted grids,

the important part is volume calculation- very big influence of the volume errors

on stress tensor.

I think in 3D case the best way is to use nonmoving Euler with

similar to FAVOR technics from FLOW-3D.

abouziar

Re: Fluid-structure interaction

Biswajit Banerjee — Sun, 12 Oct 2008 20:24:51 -0400

I would like to point out the popular "Immersed Boundary Method " from Charles Peskin's group at the Courant Institute and collaborators. For really large deformations at high speeds (for both solids and fluids) I'd also like to point out our work at Utah. A preprint (via Scribd) can be viewed below:

Fluid-Solid Interactions in Bio-MEMS/NEMS

Kilho Eom — Thu, 09 Oct 2008 11:15:00 -0400

Even though I do not have expertise in fluid-solid interaction, I would like to mention the importance of such issue in Bio-MEMS/NEMS. Specifically, micro/nano-mechanical devices for in vitro biomolecular detection are required to be operated in liquid environment, since the interactions between biomolecules occur in water. If the resonance-type mechanical device (e.g. quartz crystal microbalance (QCM), resonant cantilever, etc.) is utilized for in situ biosensor application in liquid, the fluid-solid interaction plays a key role in resonance behavior of such mechanical device. Moreover, the resonant frequency shift for a mechanical device due to biomolecular binding (e.g. protein antigen-antibody binding, DNA hybridization, etc.) is also associated with hydrodynamic loading, since biomolecular interactions is affected by water molecules (e.g. hydrophilicity change of protein due to protein-protein interactions). This phenomenon was found in case of QCM as well as resonant microcantilever. The details of such issue are well described by following references.

[1] T.Y. Kwon, K. Eom, J.H. Park, D.S. Yoon, T.S. Kim, and H.L. Lee (2007) In situ real-time monitoring of biomolecular interactions based on resonating microcantilevers immersed in a viscous fluid. Applied Physics Letters, 90, 223903; Preprint is also available at http://www.imechanica.org/node/1297

[2] S. Kirstein, M. Mertesdorf, and M. Schonhoff (1998) The influence of a viscous fluid on the vibration dynamics of scanning near-field optical microscopy fiber probes and atomic force microscopy cantilevers. Journal of Applied Physics, 84, 1782.

[3] J. Rickert, A. Brecht, and W. Gopal (1997) QCM operation in liquids: Constant sensitivity during formation of extended protein multilayers by affinity. Analytical Chemistry, 69, 1441

I believe that theory of solid-fluid interactions may be important for characterization of micro/nano-mechanical devices for their potential application to in situ biosensor operated in liquid environment.

Difficult resear area.

CAEengineer — Tue, 07 Oct 2008 16:06:32 -0400

Some of my personal opinions (might not be right):

In my understanding, FSI is a difficult research topic. However, at the same time, it is not getting enough attention because people think it is difficult but not important. Structural analytical methods are mature and accurate, but fluid behaviors are difficult to simulate. If the velocity of fluid is higher, tubulance plays important role. Modeling method of FSI is restricted by fluid models.

Biological simulation might be an important area for this kind of research.

Hope experts in this area can share their knowledge for this interesting topic.

====================

We are Collegues

Deng-Shouchun — Mon, 06 Oct 2008 03:45:23 -0400

Deng, Shouchun

My friends is working on industry based project in this regard.

RoozbehSanaei — Fri, 18 Jul 2008 12:45:10 -0400

My friend is developing a software for industry to model a machineusing this method. you can call me in this regard.

RoozbehSanaei@Yahoo.com

Lattice Boltzmann method can be used for this problems

RoozbehSanaei — Fri, 18 Jul 2008 12:37:58 -0400

Lattice
Boltzmann methods - Wikipedia, the free encyclopedia

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Boltzmann Equation to Multiscale Fluid Problems - all
11 versions »
S Succi, O Filippova, G Smith, E Kaxiras - 2001 -
doi.ieeecs.org
Vol. 3No. 6; NOVEMBER/DECEMBER 2001, pp. 26-37. Applying the
Lattice Boltzmann
Equation to Multiscale Fluid Problems Sauro
Succi ...

LATTICE
BOLTZMANN METHOD FOR FLUID FLOWS - all
11 versions »
S Chen, GD Doolen - Annual Reviews in Fluid
Mechanics, 1998 - Annual Reviews
... Full Text Annual Review of
Fluid Mechanics Vol ... that the macroscopic dynamics of
a
fluid is the ... the nonlinear macroscopic advection through
multi-scale expansions ...

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adaptive methods for multi-scale problems in fluid mechanics - all
6 versions »
R Klein, N Botta, T Schneider, CD Munz, S Roller, … -
Journal of Engineering Mathematics, 2001 - Springer
... Page 3.
Asymptotic adaptive methods for multi-scale problems in
fluid mechanics
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multi-scale problems in fluid mechanics 265
...

The multiscale
formulation of large eddy simulation: Decay of homogeneous isotropic
turbulence - all
4 versions »
TJR Hughes, L Mazzei, AA Oberai, AA Wray - Physics of
Fluids, 2001 - link.aip.org
... and JB Quincy, “The variational
multiscale method: A paradigm for computational
mechanics,”
Comput. ... TA Zang, Spectral Methods in Fluid Dynamics (Springer
...

Applying the Lattice
Boltzmann Equation to Multiscale Fluid Problems - all
11 versions »
S Succi, O Filippova, G Smith, E Kaxiras - 2001 -
doi.ieeecs.org
... We thank Achi Brandt for discussions on
mathematical aspects of multiscale methods
and Howard Stone for
discussions on the physics of fluids ... Fluid Mechanics,
vol ...

MULTISCALE
FLOW SIMULATIONS USING PARTICLES - all
7 versions »
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2005 - Annual Reviews
... Extensive reviews of nanoscale fluid
mechanics can be found ... or dynamic problems,
such as
fluid flows in ... FOR MOLECULAR DYNAMICS In multiscale
simulations, the ...

Multiscale
model for turbulent flows - all
6 versions »
D WILCOX - AIAA Journal, 1988 - pdf.aiaa.org
...
the multiscale model, it is instructive to first summarize the complete
set of
equations that constitute the model. For general compressible
turbulent fluid ...