Thick Fluid Sim is Lumpy... How do I fix this?

I have a problem with having a thick fluid resting on the floor of the domain object. I’ve tried changing the resolution of the simulation to create a very dense mesh. I have also tried a lower resolution too and it still happens.
The fluid looks as if it’s sitting on a grid because the lumps are always evenly spread and get worse the longer the fluid sits there. I have tried changing the grid levels and compressibility. Is there a work around that anyone can think of?
Why is it doing this?
I include a screen shot of my problem.
Any help would be well received.


What result are you trying to obtain would be an appropriate question to ask in this case

I am pouring a thick tar like material onto a flat roof to show how flat roofs are protected.

What is the highest resolution you’ve tried? 50 is incredibly low. It would also help if you shared your .blend file.

The fluid seems to be very bumpy at around frame 570
One thing to note about this .blend is that the fluid begins at frame 87 so when baking the fluid the domain is a box until frame 87 (this is not my problem though)
The problem is with the fluid getting “bumpy/lumpy” the longer it sits on the floor of the domain.
I’ve attached my .blend file for examination.
The highest resolution I’ve tried is 256. It seems to be worse using higher resolutions.


Fluid.blend (947 KB)

I see a couple of likely culprits here. First, you need to apply scales and rotations on your obstacle and inflow objects. Ctrl-A in Object mode. That helps a bit. Second, at the overall size of your domain object, the domain’s Real World Size might be causing some trouble. The actual dimensions of all your objects here are huge if you take the standard assumption that 1 Blender Unit=1 Meter. That would make your domain about the size of a 9 story building. You can have mismatched domain and real world sizes, but it’s usually done to fake a small sim to look huge, not the other way around. You probably need to scale everything down to correspond to their real sizes (and apply those scales of course).

Edit: Apparently I have two tabs open. This wasn’t supposed to go here…

Thanks for the help. I will look into this. I assumed perhaps a large domain would have more detail, but I guess computers don’t care about that.
Thanks guys.

They can, but the way you set it, the domain is large but the fluid isn’t. That’s kind of like zooming in too far on a picture.

To get nice looking fluid you need at least a 600Mb cache size or more. 1Gb is not uncommon in fluid sims. So there is no magic number for resolution because the resolution is linked to the longest edge of the domain box. Your domain should be tight as possible for best resolution, memory usage and shortest calculation time. Having extra ‘air’ in your domain is just a waste of time and resources.

The scaling suggestions, mentioned above, are important as well.