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how to create polar plot in journal bearing

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hello, need some help from u all to plot these polar plot. these study about pressure distribution around bearing surface of hydrodynamic journal bearing..

radius bearing : 50mm
height bearing : 50mm
clearance, c : 0.052mm

speed 600rpm , n load 10kN


3 Replies Last Post Jan 4, 2013, 5:54 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago Dec 26, 2012, 2:59 a.m. EST
Hi

it depends what you are looking for, you have ploar plots in the "more" list, but you need to define your variables, the easiest is often to define a cylindrical coordinate under Definitions. Then you can play with the Data set to create an intersection of cut planes perpendicular to your axis and your earing cylindrical surface

There is also a nice video on "results" postprocessing exampls on the main Web site

--
Good luck
Ivar
Hi it depends what you are looking for, you have ploar plots in the "more" list, but you need to define your variables, the easiest is often to define a cylindrical coordinate under Definitions. Then you can play with the Data set to create an intersection of cut planes perpendicular to your axis and your earing cylindrical surface There is also a nice video on "results" postprocessing exampls on the main Web site -- Good luck Ivar

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Posted: 1 decade ago Dec 26, 2012, 3:11 a.m. EST
thank you sir.. and can i know how to getting the pressure distribution result with constant value of z-axis which is 25 mm (middle line of journal bearing).

i have try it before in manually. here i attach the table of pressure value.
thank you sir.. and can i know how to getting the pressure distribution result with constant value of z-axis which is 25 mm (middle line of journal bearing). i have try it before in manually. here i attach the table of pressure value.


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

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Posted: 1 decade ago Jan 4, 2013, 5:54 a.m. EST
Hi

indeed no easy way to make a circular cut line on that cylinder from the data set operations (at least I didn't find out).

Then I can only propose that you cut your geometry with an internal boundary line at z=25[mm] (for that: modify our geometry cylinder and write H/2 instead of Heigh = H, then "duplicate" or "move and keep existing" cylinder with an offset along Z of H/2 => you have a cut line in the middle, a "Layer" will not work as it adds a "solid plug") and add a Definition cylindrical coordinate system (sys2) before a re-solve the model, then add a polar plot - Line graph, set the expression to sys2.phi and main expression to whatever you want to study, and select the first quadrant of the central line (at Z=25), to get the other quadrants, select the "make selection" icon, then click the Definition "Explicit1" node just made and select the tick Group by Continuous tangent

you can also write out the expression for the angle phi as atan2(y,x)

--
Good luck
Ivar
Hi indeed no easy way to make a circular cut line on that cylinder from the data set operations (at least I didn't find out). Then I can only propose that you cut your geometry with an internal boundary line at z=25[mm] (for that: modify our geometry cylinder and write H/2 instead of Heigh = H, then "duplicate" or "move and keep existing" cylinder with an offset along Z of H/2 => you have a cut line in the middle, a "Layer" will not work as it adds a "solid plug") and add a Definition cylindrical coordinate system (sys2) before a re-solve the model, then add a polar plot - Line graph, set the expression to sys2.phi and main expression to whatever you want to study, and select the first quadrant of the central line (at Z=25), to get the other quadrants, select the "make selection" icon, then click the Definition "Explicit1" node just made and select the tick Group by Continuous tangent you can also write out the expression for the angle phi as atan2(y,x) -- Good luck Ivar

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