A tuned liquid damper (TLD) is a passive control device that transfers kinetic energy from the main structure to a liquid sloshing in a tank. The mechanical description of a sloshing liquid contained in a tank requires an intricate mathematical formulation. An alternative technique describes the TLD dynamic behavior as an equivalent mechanical model comprising a series of pendulums or mass-spring systems attached to the tank walls. To validate this approach, this paper compares the discrete model to experimental results and an analytical solution for a rectangular container attached to a pendulum (pendulum-slosh problem). At first, the fundamental oscillation period of the discrete model, representing a rectangular tank, is compared to experimental data and a classic analytical solution. Finally, we compare the pendulum-slosh problem modeled as a discrete model with the analytical solution and experimental results.