On the use of stimulated thermocapillary currents and virtual walls as computational tools for natural convection simulation in enclosed spaces

•A fictitious Marangoni stress is proposed as a new approach for simulating natural convection in enclosed geometries.•Using virtual walls, the fictitious Marangoni stress is introduced as a simple constant.•No priory knowledge of Nusselt number is needed.

A new, alternative approach is proposed for natural convection simulation by means of stimulated thermocapillary currents created by virtual walls. In contrast to the well-known effective thermal conductivity model, in the proposed approach it is the mass motion due to the convective currents which is intended to be simulated and the heat flux is a consequence of such flows. As a result, no a priori knowledge of the Nusselt number is needed and thus the approach is more suitable for complex geometries. Utilizing a simplified physical model and the definition of hydraulic diameter, a generalized expression for enclosed geometries is derived which offers thermal engineers a powerful analysis tool that can use virtual walls with an associated fictitious Marangoni stress for pre-screening and estimation of Nusselt numbers.