Abstract
A Stefan flow can be generated during a phase change or reactions of a particle immersed in a fluid. This study investigates the effect of Stefan flow on the exchange of momentum (drag coefficient (CD)) and heat transfer (Nusselt number (Nu)) between the particle and bulk-fluid. Fully resolved simulations were carried out for a flow near a spherical particle immersed in a uniform bulk flow. The immersed boundary method is used for implementing fluid-solid interactions and the particle is considered as a static boundary with fixed boundary conditions. In a non-isothermal flow, the changes in thermophysical properties at the boundary layer played a role in the variation of CD and Nu by a Stefan flow further. The previously developed model for the drag coefficient of a spherical particle in a uniform isothermal flow was modified for a uniform non-isothermal flow. The model is developed based on physical interpretation. A new model is developed for the Nusselt number for a spherical particle with a uniform Stefan flow combining available models in literature. The models are validated for Stefan Reynolds number −8⩽Resf,p⩽25 and particle Reynolds number of 2⩽Ref⩽30 in gas flow (i.e. Pr≈0.7).
Highlights
Particle-laden flows have many complexities due to e.g. flow separation, particle wakes, multi-particle effects, Stefan flow effects and reactions
The main objective of the current paper is to study the effect of Stefan flow on Nusselt number and drag coefficient for nonisothermal conditions
By comparing the simulation results obtained at isothermal and non-isothermal conditions, it is possible to isolate the physical effects of the Stefan flow from thermal effects
Summary
Particle-laden flows have many complexities due to e.g. flow separation, particle wakes, multi-particle effects, Stefan flow effects and reactions. Such flows are associated with physical effects that have a wide range of length and time scales. It is currently impossible to resolve all scales in any numerical setup of practical relevance. This gap can be bridged by developing models describing the effects occurring at smaller scales (smallest physical/chemical scales). The smallest physical scales (O(10−5m)) can be studied through detailed numerical simulations. We investigate the Stefan flow effects in particle-laden flows using numerical simulations
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