The Falling in Fluid model shows a sphere falling through a fluid.  It is a supplemental simulation for an article by Pirooz Mohazzabi "Falling and Rising in Water" in the The Physics Teacher 48 (7), 478-479 (2010).  The sphere is acted on by gravitational, buoyant, and viscous drag forces acting at the interface between the fluid and the object.  At high speed, the drag force is proportional to the square of the speed whereas at low speed it is proportional to the speed.  These regimes are characterized by the Reynolds number and this model computes the viscous drag force using a phenomenological equation that depends on the Reynolds number.

The Falling in Fluid model was created using the Easy Java Simulations (EJS) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.  Double clicking the ejs_mech__fluids_FallingInFluid.jar file will run the program if Java is installed.

Please note that this resource requires at least version 1.5 of Java.