as you can see, the wind is blowing in y-direction (as shown from the picture above),
from the force plot:
the average force acting on the upper panel is about 2100 N in Z-direction,
the max. force acting on the lower panel is about -750N in negative Z-direction,
My problem is:
Is that means the force acting on the panel is upward force? with net upward force 1350N??
Actually, the back of the structure is sealed, why there is still a huge upward force acting on the panel?
Is there anything wrong with my understanding or system setting?
You should not be surprised by roofs lifted by wind even weaker than your. If you look into pressure field in ‘Solution Fields’, it will explain the lifting force.
However you still have ‘face3229’ missing from definition of Lower Panel, so actually lifting force from strong front pressure will be much bigger. In your case Z+ means lifting force, but now you possibly grasped it.
Your ‘house’ is really small, perhaps for a dog: Turbulence will develop in a dozen of seconds, so no need to run simulation for 1000 seconds.
Your big Background Mesh Box is an overkill: you can reduce it 100 times for you tiny house (but keep the mesh resolution).
In open air, for reduced tunnel size, I suggest to NOT use slip walls. Instead, use: Custom > U and P Zero Gradient > k and omega Fixed value, set respectively to k = 0.00375, omega = 3.375. That way the walls become ‘transparent’ and will not reflect pressure drop or whatever due to turbulence or wind direction. That kind of ‘transparent’ tunnel allows one to change inlet wind direction: when you try to do that in normal ‘slippy walls’ tunnel, simulation will go awry.
Thank you for your advice,
i’m now doing some modifications:
In simulation control: reduce the “end time” and “write interval” to 500s
Reduce the size of mesh box
Change the settings of the walls
and check the results later.
But in the Numerics, is the default solvers and settings suitable for my current situation?
Also, if i want to find out the total upward force acting on the entire structure, should I include all the faces (select the entire structure) in the Result Control - Forces and moments?
Dale: short answer about geometry is that AFTER meshing the STEP format or PARASOLID are ‘exploded’ into flat structure of many faces. This is not the case of STL format: you have, after meshing, still one solid (but its name is lost).
By the way, elsewhere you proposed to change the naming convention for meshed faces: I would agree, but it is not enough. Why meshing does not preserve naming of entities, present in STEP files, for instance? Then the structure of the mesh will be easier to navigate. Perhaps we can join forces to propose that?
Ahhh, but I don’t have much luck exporting good stl from Rhino, I just stick with importing Rhino .3dm files and I don’y know if Rhino has entity naming.
I am not sure I am much of a force to join with , and I definitely have my own opinions on a lot of things but I will post this as one of my ‘Dale’s Feature Polls’ and you can vote and comment on it there
Looks like you have things under control now and it looks like this is a concrete structure that just sits on the ground…
Don’t forget to take into account the moments results that would let you obtain the lifting force on the windward wall with respect to the actually weight on that windward wall (from c of g location and weight of structure).
And to confirm that the structure drag will be significantly less than the friction created between the concrete structure and the surface it is sitting on.
Thanks for your advice,
Just a question, every time when i finish mesh generation, a message appear: “Simulation assignment on the geometry is not supported for the currently selected mesh. Try to regenerate your mesh or use the mesh as simulation domain”