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Geometry for 2D-axial symmetry

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When I analyse temperature or distribution for pipe flow in 2D axial symmetry mode, should I draw all geometry (complete diameter) or draw the half of it (radius size). I draw a rectangle which has a heigth of pipe radia (not dia), and draw another rectangle on the first rectangle having a height of pipe wall thickness. I have a fluid passing through from right to left. For boundary conditions, I select the bottom line as symmetry, the left side as temperature (for analysing temp. distribution) , upside as insulated, and rigth side as convective flux (or insulated, since both have same eqn.) I want to investigate temperature distributions of fluid and pipe wall along the pipe. But I when I try to solve the problemThen temperature at the bottom decreases under the inlet temperature of the fluid while upper points in the fluid have higher temperatures. However what shohuld happen is the bottom boundary have always hottest temp. along the flow. Am I doing something wrong? Thank you...

2 Replies Last Post Jun 17, 2010, 3:58 a.m. EDT

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Posted: 1 decade ago Jun 17, 2010, 3:33 a.m. EDT
Sorry, I must correct the question. The revised version is:

When I analyse temperature distribution for pipe flow in 2D axial symmetry mode, should I draw all geometry (complete diameter) or draw the half of it (radius size). I draw a rectangle which has a heigth of pipe radia (not dia), and draw another rectangle on the first rectangle having a height of pipe wall thickness. I have a fluid passing through from left to right. Initially pipe and fluid have 300 K temp. For boundary conditions, I select the bottom line as symmetry, the left side as temperature (for analysing temp. distribution) at 500 K, upside as insulated, and rigth side as convective flux (or insulated, since both have same eqn.) I want to investigate temperature distributions of fluid and pipe wall along the pipe. But I when I try to solve the problem, temperature at the bottom decreases under the inlet temperature of the fluid while upper points in the fluid have higher temperatures. However what should happen is that the bottom boundary has always hottest temp. along the flow. Am I doing something wrong? Thank you...
Sorry, I must correct the question. The revised version is: When I analyse temperature distribution for pipe flow in 2D axial symmetry mode, should I draw all geometry (complete diameter) or draw the half of it (radius size). I draw a rectangle which has a heigth of pipe radia (not dia), and draw another rectangle on the first rectangle having a height of pipe wall thickness. I have a fluid passing through from left to right. Initially pipe and fluid have 300 K temp. For boundary conditions, I select the bottom line as symmetry, the left side as temperature (for analysing temp. distribution) at 500 K, upside as insulated, and rigth side as convective flux (or insulated, since both have same eqn.) I want to investigate temperature distributions of fluid and pipe wall along the pipe. But I when I try to solve the problem, temperature at the bottom decreases under the inlet temperature of the fluid while upper points in the fluid have higher temperatures. However what should happen is that the bottom boundary has always hottest temp. along the flow. Am I doing something wrong? Thank you...

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago Jun 17, 2010, 3:58 a.m. EDT
Hi

2D axi assumes you restrict yourself to the right X>0 side (first and forth quadrants)

hope this helps
Ivar
Hi 2D axi assumes you restrict yourself to the right X>0 side (first and forth quadrants) hope this helps Ivar

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