An interface-resolved phase-change model based on velocity decomposition

An interface-resolved phase-change model is proposed in the interface-capturing framework based on the coupled level-set and volume of fluid (CLSVOF) method. A velocity decomposition method is employed to ensure the numerical stability and accuracy of interface propagation. Specifically, the velocity u is decomposed into the potential part u tilde associated with the phase change and the remaining rotational part u over line . The potential velocity u tilde is computed by solving a Poisson equation. A modified momentum equation is derived to solve the rotational-part velocity u over line , which is divergence-free. The momentum equation is solved using the Computational Air-Sea Tank (CAS-Tank) developed previously by Yang et al. [1]. To evolve the interface and ensure the mass conservation, a continuous interfacial velocity ur is constructed by adding the velocity u circumflex accent associated with the volume change of liquid (or gas) to u over line , where u circumflex accent is computed by solving a Poisson equation with constant coefficient. The proposed method is verified in the context of the two-dimensional (2D) droplet with constant evaporation rate, one-dimensional (1D) Stefan and sucking problems, 2D droplet evaporation at saturation temperature, 2D droplet evaporation below saturation temperature, and a three-dimensional (3D) evaporating droplet falling under the gravity. The results show that the proposed method is accurate and stable. The numerical method is also validated by simulating an evaporating droplet falling under the gravity and the numerical results are found to be in agreement with the results in the literature. The interaction of two evaporating droplets is also simulated in a 3D domain to show the capability of the proposed method in solving 3D problems.(c) 2022 Elsevier Inc. All rights reserved