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-   -   How to apply the temperature boundary condition on the outside of the mould? (http://www.cfd-online.com/Forums/flow-3d/76257-how-apply-temperature-boundary-condition-outside-mould.html)

alefem May 19, 2010 11:04

How to apply the temperature boundary condition on the outside of the mould?
 
Hi, All
I am trying to simulate a simple sand casting process, in which hot melt flows in the cavity of the mould and cooling channel is applied on the outside of the mould.
I would like to set the outside boundary of the mould a fixed temperature as a cooling condition, however, when I use “Model setup-Boundaries-Mesh Boundaries-Block-Wall or others”, it doesn’t work at all no matter what temperature I set.
So my question is that how to apply the temperature boundary condition on the outside of the mould?

ck5285 May 21, 2010 02:37

you can set initial solid temperature for the mold under Meshing & Geometry -> Component -> Initial Conditions -> Temperature. But this is just an initial temperature for the solid object. For isothermal temp setting you may want to try Boundaries -> Wall -> Thermal Boundary Options -> Temperature. Hope this help.

alefem May 21, 2010 05:03

Quote:

Originally Posted by ck5285 (Post 259654)
you can set initial solid temperature for the mold under Meshing & Geometry -> Component -> Initial Conditions -> Temperature. But this is just an initial temperature for the solid object. For isothermal temp setting you may want to try Boundaries -> Wall -> Thermal Boundary Options -> Temperature. Hope this help.

Yes, I just did that, but it didn't work.
The geometry is very simple, a rectagular mould with a cylinder cavity, I set the 4 sides of the mould as "wall" boundaries and change the temperature in the "thermal information", but the results didn't change at all even the wall temperature is unreasonable high or low.
I am so confused

alefem May 21, 2010 11:51

The Prepin data is as follows, in which the wall temperature is unreasonable, I just want to check if it works or not.



Title
This is a sample input file
$xput
remark='units are ...',
twfin=100.,
itb=1,
ifenrg=2, iwsh=0, ihtc=2,
ifsld=1,
iedt=2, pltfrc=0.05,
delt=1e-6,
$end
$limits
$end
$props
rhof=2437.,
rhofs=2680., cv1=1194., cvs1=963., thc1=116.8,
thcs1=152., clht1=3.89e+05, ts1=539.6, tl1=615.9,
tniyam=-1., tsdrg=1., mui=0., mu1=0.0012,
muc00=0., muc0=1., muc1=0., muc2=0.,
muc3=0., muc4=0., mutmp1=0., mutmp2=0.,
mutmp3=1., muthk=0., muthn0=0., muthn1=0.,
teut=0., cexf1=0., cstar=0., dratio=0.,
pcoef=0., fluid1='Aluminum Alloy A357', units='SI',
$end
$scalar
$end
$bcdata
wl=2, wr=2, wf=2, wbk=2,
wb=2, wt=5, pbct(1,6)=243.7, tbct(1,6)=620.,
tbct(1,1)=1e7, hwall1(1)=1e6, hwall2(1)=1e6,
hwobs(1)=1e6,
$end
$mesh
nxcelt=35, px(2)=0.8,
nycelt=35,
nzcelt=40, pz(2)=1.5,
px(1)=-0.8, py(1)=-0.8, py(2)=0.8, pz(1)=-0.4,
$end
$obs
avrck=-3.1,
nobs=1,
iob(2)=1, ioh(2)=1, xl(2)=-0.8, xh(2)=0.8,
yl(2)=-0.8, yh(2)=0.8, zl(2)=-0.4, zh(2)=1.5,
magnx(2)=1., magny(2)=1., magnz(2)=1.,
subcmpid(2)='Rectanguar', material(1)='Steel H-13', twobs(1,1)=294.,
kobs(1)=28.6, rcobs(1)=3.5618e+06, hobs1(1)=20000., hobs2(1)=-1.,
ocang(1)=90.,
obsid(1)='Moud and cavity',
subcmpid(3)='Cylinder', iob(3)=1, ioh(3)=0, zl(3)=0.,
zh(3)=1.5, rah(3)=0.4, magn(3)=1., magnx(3)=1.,
magny(3)=1., magnz(3)=1., rotx(3)=0., roty(3)=0.,
rotz(3)=0., trnx(3)=0., trny(3)=0., trnz(3)=0.,
hobv1(1)=0., hobv2(1)=0., hobv3(1)=0.,
$end
$fl
$end
$bf
$end
$temp
$end
$motn
$end
$grafic
$end
&HEADER
PROJECT='Rectangular',
/

$parts
$end
Documentation: general comments, background, expectations, etc.
#start tables:
#component(1):
#end component(1)
#fluid1:
#end fluid1
#fluid2:
#end fluid2
#end start tables

ck5285 May 24, 2010 20:52

strange i did try myself, it also didn't work out with V9.4.1. So anyone have this problem before?

alefem May 25, 2010 05:32

CK, I finally found the problem.
Even I used a so high temperature and long cooling time, the heat transfer coefficient l used above was still not big enough, comparing to the distance between the heat source and the boundaries.
Increase the thermal conductivity or shorten the distance of the boundaries, the boundary temperature will play a part.


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