The fluid may be compressible or incompressible. In fact, thermodynamics is typical of compressible flows and degenerates in incompressible flows. The soft tissues are also viscoelastic, incompressible and usually anisotropic. For incompressible isotropic hyperelastic materials, the strain energy density function is formula 37. Bernoulli's equation is fundamental to the dynamics of incompressible fluids. When these collisions are statistically negligible (incompressible), results from these ideal equations are still meaningful. Then, for an incompressible and Newtonian fluid, due to Helmholtz theorem, we can determine v. Gases under certain conditions can be approximated as incompressible. The condition for stability of an incompressible fluid is that "density decreases monotonically with height". Muscle is composed primarily of an aqueous liquid that is essentially incompressible at physiological pressures. The above equation applies only to fluids that can be treated as incompressible. Liquids are treated as incompressible under almost all conditions. In general, equation (2) is applicable only for incompressible flows. The above equation applies only to conditions that can be treated as incompressible. For incompressible flow, the divergence of the volume flux is zero.