FLOW FOCUSING INSTABILITY IN A SOLIDIFYING MUSHY LAYER

The stability of the flow of interstitial Liquid in a mushy layer driv en by expansion or contraction upon solidification is analysed. The fu ll perturbation equations are reduced in a particular aymptotic limit that allows the principal mechanisms controlling instability to be ide ntified. Comparisons are made with the acid-etching instabilities in p orous rocks. The full equations are then solved to determine the param etric dependences of the instability. It is found that, though the pot ential for instability exists, it is unlikely to occur in practice.