We present a Weakly Compressible SPH (WCSPH) formulation with a temporally
variable speed of sound. The benefits of a time-varying sound speed formulation
and the weaknesses of a constant sound speed formulation are worked out. It is
shown how a variable sound speed can improve the performance, accuracy, and
applicability of the WCSPH method. In our novel Uniform Compressible SPH
(UCSPH) method, the required artificial speed of sound is calculated at each
time step based on the current flow field. The method's robustness,
performance, and accuracy are demonstrated with three test cases: a
Taylor-Green vortex flow, a falling droplet impact, and a dam break. For all
showcases, we observe at least similar accuracy as computed with WCSPH at
strongly improved computational performance