Multi-step Ice Accretion by Immersed Boundaries

Abstract

<div class="section abstract"><div class="htmlview paragraph">The paper describes a tools’ suite able of analyzing numerically 3D ice-accretion problems of aeronautical interest. The methodology consists of linking different modules each of them performing a specific function inside the ice-simulation chain. It has been specifically designed from the beginning with multi-step capability in mind. Such a feature plays a key role when studying the dynamic evolution of the icing process. Indeed, the latter has the character of a multi-physic and time-dependent phenomenon which foresees a strong interaction of the air- and water fields with the wall thermodynamics.</div><div class="htmlview paragraph">Our multi-layer approach assumes that the physical problem can be discretized by a series of pseudo-steady conditions. The simulation process starts with the automatic generation of a Cartesian three-dimensional mesh which represents the input for the immersed boundary (IB) RANS solver. Once obtained, the air-phase is used by the Eulerian tool to solve the transport of the water-phase on the same domain-grid. Both the volumetric solvers share the same unstructured data management and the finite-volume (FV) approach which is based on locally refined Cartesian meshes.</div><div class="htmlview paragraph">Part of the research effort is devoted to the development of a thermodynamic 3D method which solves the surface liquid-film by Messinger balances of mass and energy. The main outputs are the equilibrium temperature and the mass of ice. The latter is used to compute the local ice-height for accretion purposes. A Lagrangian modification of the geometry is applied at each step by moving the wall vertices along the local unit normal vector. The modified 3D surface is passed again to the automatic mesher for renewing the computational loop. The accuracy and the limits of the present method are discussed by analyzing the results on three-dimensional benchmarks proposed in the framework of the 1st ice prediction workshop (IPW).</div></div>