Fig. 4. Rise of a 2D cylindrical porosity wave with constant bulk viscosity  b´ = 1. The background viscosity is 2%, the maximum porosity is 6%. Rm = 10, Rtn = 0.0288, no melting and freezing is assumed. All quantities are non-dimensional.  The non-dimensional compaction length based on the background porosity is 0.01667. a) melt fraction, b) divergence of the matrix velocity, c) vertical segregation velocity, d) horizontal segregation velocity, e) buoyancy contribution of the vertical segregation velocity, f) compaction contribution to the vertical segregation velocity.