For the purpose of choosing the most efficient conditions of underwater spark discharges one must acknowledge various properties of medium that influence the results. One of such properties is compressibility of liquid.
This work presents and compares numerical models for the cylindrical conducting spark channel formed by the electrical breakdown of water gap between a pair of electrodes for incompressible and compressible liquids. Models describe an evolution of hydrodynamic characteristics, namely: radius of spark channel, velocity and pressure on the wall of the spark channel and the resulting cavity, were coupled with parameters of the discharge circuit for further experimental testing.
Results obtained for the two models show slight differences in magnitude and dynamics of estimated parameters.