Why does the water keep escaping in my fluid simulation? I am trying to do a water simulation. I have a small cup that I have created in blender (as an obstacle) and my water source (just an oval). My domain box is large enough to encompass both the glass and the water source:



Here are my settings for my domain:



I am using the default blender renderer. I have the cup setup as a collision for a water simulation and I have the sphere inside of the cup set as a fluid in a fluid simulation. When I bake the scene, here is what I get:



As you can see, the water is going through the cup, but the cup is having an effect on the water. Here is the rendered view:



How can I keep the water in the cup??
As others have mentioned, it's the resolution that's key here. However, I see that you've baked at two separate resolutions: 120 for final and 45 for preview.

You can see from the render view that the "final" quality bake has less "escaping" water. To preview that in your viewport without rendering, change the "Viewport display" dropdown to "Final." The downside of this is that it may slow down your viewport.

If you want even better quality, you could either:


increase the resolution, or:
Alt-D to linked-duplicate the cup object, then scale it down a tad (maybe 95%) and position it inside the real cup. Turn off the viewport and render visibility. Set its parent to the "real" cup, but mark both as collision targets (Physics &rarr; Fluid &rarr; Obstacle). This will essentially shrink the bounds of your cup and may or may not completely solve the problem.