simulating arrow illusion now i need to simulate the arrow illusion which is,an arrow drawn on a sheet of paper that is put 4 inches behind a glass and then the glass will be filled with water and look at the arrow through the glass we should find that the arrow direction is reversed due to refraction of light(you can check that on youtube). I know how to simulate fluids, but how do i simulate that refraction? How can i simulate what happens to the arrow?
Model the glass, it is important that it is solid and has a thickness.
Simulated or modelled, the fluid has to intersect the glass. However, even with not-intersecting glass, the arrow will refract correctly.
Apply a Refraction BSDF to both objects (the glass and the fluid) in Cycles Material Nodes.




As you can see in the image, the fluid object intersects the glass. The fluid mesh is partially in between the inner and outer wall of the glass.