Abstract
We introduce a novel model for the incompressible viscous fluid draining from a coupled tank and capillary tube system. By physics laws, we set up a nonlinear differential equation, which governs this model, and derive its parametric solution. Performing asymptotic. analysis, we show that existing well-known models can be redeveloped from our new model. In addition, we analyze the maximum deviation between the new model and the exponential decay model. Experimental results back up our analytic analysis.