We desire the heat flux through the boundary S of the subregion V , which is the normal component of the heat flux vector φ, φ n̂, where n̂ is the outward unit · normal at the boundary S. Hats on vectors denote a unit vector, n̂ = 1 (length 1). | | If the heat flux vector φ is directed inward, then φ n̂ < 0 and the outward flow of · heat is negative. To compute the total heat energy flowing across ...

A systematic study of the local convective heat transport in turbulent thermal convection is carried out in small-aspect-ratio cells filled with water. The local convective heat flux is obtained from the simultaneous velocity and temperature measurements over varying Rayleigh numbers and spatial positions across the entire convection cell. Large fluctuations of the local convective heat flux ar...

Using a quasi-static approach valid for Stefan numbers less than one, we derive approximate equations governing the movement of a phase change front for materials which generate internal heat. These models are applied for both constant surface temperature and constant surface heat flux boundary conditions, in cylindrical, spherical, plane wall and semi-infinite geometries. Exact solutions with ...

In this study, process enhancements achieved by the use of 3D printed feed spacers based on triply periodic minimal surfaces (TPMS) were comparatively assessed using two most common membrane distillation (MD) configurations: air gap (AGMD) and direct contact (DCMD). The MD performance was impact spacer design (TPMS vs. commercial spacer) flux channel pressure drop, their consequent levelized co...

The exchange of trace gases such as carbon dioxide or methane between the atmosphere and the ocean plays a key role for the climate system. However, the investigation of air–sea gas exchange rates lacks fast and accurate measurement techniques that can also be used in the field, e.g., onboard a ship on the ocean. A promising way to overcome this deficiency is to use heat as a proxy tracer for g...

Effect of time dependent normal transpiration on the problem of unsteady viscous flow and heat transfer in the vicinity of an axisymmetric stagnation point of an infinite circular cylinder moving simultaneously with time-depended angular and axial velocities and with time-dependent wall temperature or wall heat flux are investigated. The impinging free stream is steady with a strain rate . A re...