Drag force and heat transfer coefficient for Stefan flow-affected non-spherical particles in supercritical water

The fluid and non-spherical particle interaction exists widely in multiphase systems and is more complex due to the shape factor and the Stefan flow that emits from the particle surface will further affect the mass, momentum, and energy transfer between the particle and the fluid. Works about the drag coefficient and Nusselt number relations for Stefan flow-affected non-spherical particles are rare. Motivated by this fact, a particle-resolved direct numerical simulation study of Stefan flow-affected non-spherical particles in supercritical water is carried out to investigate the flow and heat transfer process. The sphere, ellipsoid, cylinder, cube, and cuboid particles are considered in steady-state regimes corresponding to Reynolds numbers from 10 up to 200. This work analyzes the pressure and friction drag coefficients of the particles and illustrates the flow, velocity, and temperature distribution around the particles. The drag coefficient and Nusselt number show significant differences between different shape particles, and Stefan flow further reduces the drag force and Nusselt number. The Reynolds number, particle shape, and Stefan flow both influence particle-fluid interaction: introducing two particle shape descriptors, the drag coefficient depends primarily on the average sphericity (Φ_Av), while the crosswise sphericity (Φ_⊥) influences the Nusselt number. The new fitting formulas are developed for the drag coefficient and the Nusselt number of the Stefan flow-affected non-spherical particles.