Yoav Tsori

The longitudinal viscosity which may be measured via attenuation of ultrasound, is discussed. It was observed that for a compression wave in a liquid, individual molecules can move parallel or perpendicular to the direction of wave propagation. The existence of these two modes means that energy dissipation depends on two independent quantities; hence there are two fundamental viscosities. The pressure dependence of x may also be of use in block copolymer melts such as lamellar phase.