Performance of passive scalar method in heat transfer simulation of a two-dimensional droplet focusing on the parasitic temperatures.

The pseudopotential models are very convenient, flexible and robust for practical purposes of two-phase dynamics, but the presence of spurious velocities is inevitable due to the limited discretization of gradient terms, and large amount of intermolecular forces at the interface of liquid and gas phases. The existence of such velocities, in addition to creating counterfeit flows, causes errors in obtaining the temperature field and solving the energy equation. Here, two models (Li (Phys Rev 89(5):053022, 2014) and Kupershtokh (Phys Rev E 98(2):023308, 2018)) are examined to show their capability in weakening and reducing the temperature parasites arising from the spurious velocities. Results are presented for a stationary droplet, which show the good performance of the exact difference method in reducing the parasitic temperatures. Also, the Marangoni phenomenon is simulated to validate the solution of the temperature field in the two-phase flow, which expresses the movement of droplet caused by the surface tension gradient. For more complicated problem, the Rayleigh–Bénard convection is simulated and effects of density ratio, Rayleigh number, and contact angle on the average wall Nusselt number and the average temperature of the droplet and vapor phases are investigated. The results of this work show the capability of the improved passive scalar method in simulating the two-phase heat transfer problems. [ABSTRACT FROM AUTHOR]