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-   -   Reference Values for Troughs @ variable Angle? (http://www.cfd-online.com/Forums/fluent/67395-reference-values-troughs-variable-angle.html)

 hornig August 13, 2009 13:17

Reference Values for Troughs @ variable Angle?

hi there,

I need some help of you expertes :).
I did 2d-meshes of parabolic troughs at certain angles (0,30,60,90,190 degrees) and let fluent do its magic.

to illustrate, what it looks in basic I added a picture.
I just need a crossection of this parabolic trough and I put in this for reference values.

depth=12m
length=6m=apterture
area=depth*length=72m
and the rest was left in default setting.

so, the problem is, that the pressure coefficients are near their estimated area, except the 0° one (the open area is vertical upwards). this value is so far of, that I don't know, what I did wrong.
I chacked the 180° one and this is okay.

so I'm pondering, where the error is. I print the forces and stuff by "report->forces->x/y"

so my guess is, that something is wrong with the reference values. the given values are used for all angle-modes, but I din't know for sure, it the length for example will change. and the area is, as far as i know, the projected area from velocity direction, so that would make the area in image #1 Area=length*depth, but Area=height*depth in image #2.
and what is, when there are different angles, like in #4?

 kaabya April 12, 2014 22:26

hi there,

I need some help of you expertes .
I am studying wind load on a parabolic solar concentrator at certain angles using Fluent.

I choose to start with the 2D simulation in order to evalate the drag and lift coefficient.

I have some troubles :

1. I don't find a logical drag coefficient value. It seems related to the references values. How can I set up those values in my case ?

2. If the 2D simulation is sufficient to find a good results ?