Learning Forum

[Hanantyodut]

can somebody tell me what's wrong with this condition? this is a rotating i've tried the interface setting, boundary condition setting, change the mesh method to polyhedra, cell zone setting.

in the result, i've tried to change the scale of the temperature as user specified but still in the wrong pattern (and have a hole temperature distribution)

the 1st upper picture which is the result of my analysis...

the 2nd below picture which is the correct result. (using the same data & input)

i'll be really greatful for somebody who can give me solutions and some explanations, thanks.

[Rob]

Maybe give us some details? Perhaps starting with what it is? n

[Hanantyodut]

i'm sorry for the lack of information, it's a rotating heat exchanger (air preheater, tri-sector type), with 3 different condition (temp,pressure, mass flow) for the same fluid (air)n

[Rob]

Which parts are rotating? If you review the flow field how does that compare, both to the earlier work and what you'd expect to see?n

[Hanantyodut]

For the rotating part, which is in the middle, the other 6 part (3 part each side, primary air, secondary air, flue gas) are the fluid domain. at first i expect the flow inside the middle part (Porous fluid, solid material : steel) were to be rotating....nand when i saw the result domain (the end of each fluid side) i saw some clear area that have no streamline flow through them, here is the example of the view at lower RPM : nnthank you so much for your attention, i'm really thankful and hope to get the solutions for this problem.n

[Rob]

Check the interface conditions, and make sure you've labelled all of the surfaces correctly. I'd plot each set separately to see if one's missing. n

[Hanantyodut]

thank you for your response, i've already labelled all the interface between rotor middle part dan the fluid domain at each inlet/outlet sides. and all the wall which act as the separator i've set them as coupled wall between 3 fluids. And for the interfaces i've set them as periodic boundary conditionnn

[Rob]

Why periodic, doesn't flow pass through the system once? Very carefully look at what is wall and what isn't, looking at the shear number of bc's I think there's ample scope for errors to creep in to the set-up. n

[Hanantyodut]

thank you, may i ask at what setting/setup option to cause the interface become a frozen rotor?because yes it's rotating continuosly that means the setting of my interface is wrong and actually not periodic ones....nfor the wall, i'm already check all of it and from my assumption it's correct? i'm sorry , suggestions are welcome...nthis is the wall that separate the 3 fluids, the hub in the center of the APH, and the outer wall of the fluid and the rotor.nthank you so much.n

[Hanantyodut]

the wall inside the fluid domain (yellow) i set them coupled in the setting. nfor the wrong temperature distribution do you have any advice or explanation? i would be really thankful and grateful to anybody for some suggestion and solution for this problem..n

[Rob]

If it's a wall try and model it as such, for the sliding zones use the non-conformal interface(s). There's a tutorial in the Fluent help that's very good: it's a mixing tank but the basic physics & set-up will help. n

[Hanantyodut]

thank you, that means that my simulation time model in transient? do the middle part should have mesh motion? or frame motion for it's rotational movement enough?nand for the non-conformal mesh means the geometry of the middle rotor must partially overlap the both fluid domains (inlet&outlet)?n n

[Rob]

I assumed it was rotating about the axis, with inlet(s) at one end and outlet(s) at the other. Interface zones touch on the surface, so overlap in that respect, the volumes do NOT overlap. n

[Hanantyodut]

thank you for your response, i'm sorry for the inconvenience...nmy interfaces already touch on the surface, does that means the mesh type is sliding meshes? and for the simulation time method should use the transient type?nthank you so much..n

[Rob]

It means you have the option to use sliding mesh, and if sections are rotating at different rates it'll be transient. n