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I want to calculate drag force at special angle on a sphere . There are some grooves on the sphere and these groove have a special angle on the sphere. In other words, I want to calculate drag force on the these grooves. How can I do it in Fluent?

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user19061
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I believe under Results>Reports>Forces, you can calculate the force on a chosen surface in a particular direction vector (by providing x,y,z coordinates). Does that help?

Time4Tea
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  • Thanks, but how can I provide x,y,z coordinates in Fluent? Please see y-z coordinate in above picture. Therefore, direction vector is as follows: y----> -cos teta and z---->-sin teta and x---->0 .........teta=angle Is it OK? – user19061 Jul 25 '18 at 19:36
  • Direction of flow is in direction (or parallel) of grooves. please see second picture in above – user19061 Jul 25 '18 at 20:00
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    @user19061 in the 'Force Reports' dialog box, you input what direction vector you want to calculate, then Fluent will give you the total resultant force vector, as well as the force on the chosen surface in the direction vector you specified. – Time4Tea Jul 25 '18 at 21:13
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    @user19061 however, it might help if you could clarify further about the flow situation. Is this a full 3D model of a grooved sphere, with flow coming from the positive z direction? If so, for example, it might better to request the torque acting on the whole sphere, and the drag force acting on it. – Time4Tea Jul 25 '18 at 21:16
  • No, Flow is coming from the negative z direction, of course with a special angle (90-theta) and with respect to z direction and yes, this is a full 3D model of a grooved sphere – user19061 Jul 26 '18 at 18:45
  • If drag is a force acting opposite to the motion of Fluid, therfore, I should change direction vector as follows: y----->+cos theta z----->+sin theta .....Is it correct? – user19061 Jul 26 '18 at 18:53
  • In fact, Firstly, i select my surface, then, I change the direction vector . – user19061 Jul 26 '18 at 20:01
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    So, this isn't just 2 grooves, but a series of grooves, equally-spaced around the circumference of the sphere? In that case, the angle of the groove faces will be different for each groove and, furthermore, the groove faces may not be planar, which might further complicate the situation. – Time4Tea Jul 27 '18 at 13:25
  • Yes, You are right. this isn't just 2 grooves and yes, there are a series of grooves, equally-spaced around the circumference of the sphere. Regarding groove faces, I have doubt, I think you are right. Isn't it enough to select groove faces in Fluent and write values for y and z direction vector? should these groove faces be planar? Do you have any suggestion or idea that what do i do in this case? – user19061 Jul 27 '18 at 18:52