| Author | Message | |||
     penja69 New member Username: penja69 Post Number: 1 Registered: 03-2010 |
Hello everybody, sorry for my bad english. Iīve got this problem to solve, but there is one boundary condition that I donīt know how to write. Thereīs a variation of one excercise in the gunnar backstromīs book (def50.pde) a semicircular rod of cooper with electricity (it appears heating) its inside a concrete body. this concrete body has diferents temperatures (To, T1). Ok thatīs all right, but the problem appears in the left face of the concrete. There is a constant thermal flux... so there is where is donīt know how to continue. I think iīm very close to the resolution but i have doubts. So the question is that. How can apply a thermal flux (i.e. Fo) to that face? Here is a drawing and the excercise Thank you very much. Benjamin 
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| rgnelson Moderator Username: rgnelson Post Number: 1334 Registered: 06-2003 |
The "Natural(dtemp)" boundary condition will specify the outward normal component of fluxd_x on left and right faces (see Natural in the Help Index). So this is the BC you need to apply. I should point out that this is a physically unrealizable condition. You would need to have a temperature control and a flux sensor on the left boundary and raise or lower the driving temperature to adapt to changing flux conditions. But FlexPDE will do it if you say so.... | |||
| penja69 New member Username: penja69 Post Number: 2 Registered: 03-2010 |
Thanks, but you mean that I should put this: BOUNDARIES region 'concret' start 'externo' (-Lx,-Ly) value(dtemp)=273 load(u)=0 load(v)=0 line to (Lx,-Ly) value(dtemp)=100 value(u)=0 value(v)=0 line to (Lx,Ly) value(dtemp)=273 load(u)=0 load(v)=0 line to (-Lx,Ly) natural(dtemp)=Flux load(u)=0 load(v)=0 line to finish region 'cooper' k=45 heat=1e6 start (-r0,0) line to(r0,0) arc (center=0,0) angle=90 to (0,r0) arc (center=0,0) angle=90 to finish But how I define Flux? I go to DEFINITIONS and write Flux=Number or Flux= Some function. Excusme but I'm reasonably new at Flex, and this problem is part of an examination (thatīs why itīs imposible in real life!). Thats why Iīm trying to understand every part of it. Thanks a lot and I appreciate your answer. By the way I canīt find the Help index |
