Consistent energy-stable method for the hydrodynamics coupled PFC model

초록

In this study, we propose an efficient mathematical equation to describe incompressible fluid flow-coupled crystallization. By using the L-2-gradient flow, the evolutional equation is derived from an energy functional and a nonlocal Lagrange multiplier is introduced to preserve the total mass. Various physical phenomena of colloidal crystals can be modeled using a generalized nonlinearity and the fluid dynamics are described by incompressible Navier-Stokes (NS) equations. To efficiently manage the nonlinear and coupled terms in this complex fluid system and maintain the discrete version of the energy stability, we develop a linear, second-order time-accurate, and energy-stable numerical method for the fluid flow-coupled phase-field crystal model. The energy stability of the discrete method is estimated. In each time step, all variables are completely decoupled, and we only need to solve several linear elliptic-type equations. We adopt a relaxation method to correct the energy. The main merits of this study are as follows: (i) a simple fluid flow-coupled crystal equation with generalized nonlinearity is derived; (ii) the proposed scheme not only satisfies the energy stability but also achieves improved consistency; and (iii) the calculation in each time step is highly efficient in implementing the proposed scheme. Numerical experiments, including flow-coupled phase transition, crystallization in shear flow, and sedimentation of crystals, are performed to validate the accuracy, stability, and superior performance of the proposed method.

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