openfoam in welding applications - chalmershani/ofgbg12/slides/alirezajavidi.pdfopenfoam in welding...

OpenFOAM in Welding applications

Gothenburg Region OpenFOAM User Group Meeting, November 14th, 2012

Alireza Javidi1

1University West, Department of Engineering Science, Trollhättan

1. Arc2. Energy coupling between solid and fluid3. Arc and coupling4. Melting and phase change 

Sketch of the cross section of a TIG torch

Tungsten Inert Gas welding 

Picture of a TIG torch

Ar shielding gas inlet 

Governing equations: thermal fluid part

•(Steady) continuity equation

0 u(T)

•(Steady) momentum conservation equation

hTuhhu )( (T)(T)

BJPIuTuuT T

)(

32)()(

•(Steady) enthalpy conservation equation

uuuu (T)(T)

h

TeCJkTQEJuPPu

p

Brad )(2

5)(

Joule heatingTransport ofelectron enthalpy

Lorentz force

Governing equations: electromagnetic part

Electric potential :

with:

VE

V)( TJ

0)( VT

: current densityJ

)(T : electric conductivity

Magnetic potential :A

V

with:

VTA 02 )(

AB

Argon plasma density as function of temperature.

Specific heat as function of temperature

Argon plasma electric conductivity as function of temperature

Ar shielding gas inlet 

CathodeTip

Cathodea

ABCathodea

BCAnode Nozzle Inlet Outlet

u 0 0 0 0 0 parabolic

h or T 20000K Linearb linearb linearc 0 300K 0

V or J 0 0 0 0

A

Temperature along the radial direction, 1 mm above the anode

chtMultiRegionFoam 

The  solver  is  based  on  combination  of heatConductionFoam and  buoyantFoamfor  conjugate  heat  transfer  between  a solid region and fluid region.

“0”“topAir”

“U”“T”“p”

“bottomSolid”“cp”         “K”“T”“rho”

“constant”regionProperties“topAir”

“polyMesh”thermophysicalPropertiesg

“bottomSolid”“polyMesh”   

“system”controlDict“topAir”

fvSystemfvSolution

“bottomSolid” fvSystemfvSolution

= ∑

1. Energy balance at cathode/sheath interface2. Energy balance at sheath/presheath interface3. Current density conservation