solid-fluid interaction 2

[ywioywio]

dear all,

i want to simulate the solid-fluid interaction and be able to calculate the hydrostatic pressure of the fluid. my model consists of a closed cylinder completely filled with fluid, and the cylinder will be deformed in a certain way, such that the hydrostatic pressure of the fluid increases.

Which fluid elements should i use for this problem

thanks

 

[elogesh]

Hai,

I think you are interested in fluid-structure interaction using different physics(strcutural and flow). There is an example in ansys manual regarding the same.

For each time step,solve for the flow extract the fluid forces(normal as well tangential forces) on the wall.Then move to the structure and evaluate the deformation using the fluid forces.Then repeat the process for total time using *do loop.

The problem given in ansys manual is for steady-state.

Regards,
E.Logesh

 

[ifegermany]

Hello ywioywio,

to get the hydrostatic pressure with a
non-flowing configuration, calculate the
deformation of the mechanical containment,

and then calculate hydrostatic pressure h.p.
at desired point/locations inside fluid
or at wall, by hand

h.p.= density*gravity*ls
ls = local heigth to free fluid surface

consider that with e.g. water
10 meters water column yield 1 atm of additional
pressure - 1 atm being about 100kN/m^2 or 1 bar

If you consider a few N/m^2 a change in pressure
(depends on application)or you have a large
heigth of liquid with significant deformations,
that might make a difference locally, between
deformed/undeformed h.p. Otherwise take the
undeformed calculated h.p. and you need not
perform ANSYS structural deformations.

Fluid-structure-interaction FSI is generally
for flow situations, were a mechanical part
interacts with fluid forces, this can be
approached in several ways in ANSYS


Frank Exius
IFE bei Bonn Germany

http://www.ife.subito.cc

+49\2642\980409
Numerische Simulation FEM Berechnung ANSYS
Digital Virtual Prototyping Outsourcing

 

[ywioywio]

Hi,
thanks for your advices, guys
i think my previous question is rather vague

my 3D hollow cylindrical model is completely closed (i.e acts like a container or tank fully filled with liquid)
displacements will be apllied to the solid cylinder alone, and the fluid is initially at rest(non-flowing).

at the end of the day, results for stresses in the solid and hydrostatic pressure of the fluid are required.

when i look at the ansys manual, FSI are always used for flowing fluid (with initial velocity), so i'm wondering if you guys have any idea how i can go about with my analysis

Thanks alot
i appreciate your help

 

[elogesh]

Hai,

Sloshing of the fluid on the walls has to be done if the tank is moving one.What I mean the tranfering of liquid through road transportation involves movement of the liquids, which disturbs the structure and again in turn structure start disturbing the fluid.
If it is a stationary tank, then simple linear structural analysis will do the purpose.

Regards,
Logesh.E

 

[ifegermany]

if the container is 100% filled with
liquid, you wouldn't get sloshing,

if the structural deformations are static:
you just calc the h.p. as mentioned

if the struct deform's are dynamic:

the fluid mass yields a pressure force
on a side of the container:

you may just calc the fluid mass
and add it's inertial effect by modeling
a mass element at the fluid centroid,
use coupling CP to position the mass
between the bounding containers wall nodes

coupling those nodes which receive inertia
induced pressure from the liquid, try some
configurations, delete CP's were the liquid
mass tears the nodes (as water can only produce
a positive pressure on a wall)

Frank