Spherically symmetric expansionfree distributions are systematically studied. The whole set of field equations and junction conditions are presented for a general distribution of dissipative anisotropic fluid (principal stresses unequal), and the expansionfree condition is integrated. In order to understand the physical meaning of expansionfree motion, two different definitions for the radial v...

Aims. To quantify the transient growth of nonaxisymmetric perturbations in unstratified magnetized and stratified non-magnetized rotating linear shear flows in the shearing sheet approximation of accretion disc flows. Methods. The Rayleigh quotient in modal approaches for the linearized equations (with time-dependent wavenumber) and the amplitudes from direct shearing sheet simulations using a ...

We study the shearing motion of a slab consisting of an incompressible nonlinearly viscoelastic material of diierential type. We describe reasonable general constitutive restrictions that ensure that the strain is bounded during any motion lasting a nite length of time. We brieey sketch how this simple property, which is easily veriied, ensures that the governing initial-boundary-value problems...