Experimental and numerical analysis of the boundary layer on a vertical plate at low temperature differences

The problem of heat convection from surface to air at very low temperature differences has been solved by experimental/numerical approach. The laser-based probing technique of laser beam deviation detection was developed for the measurement of air refractive index gradients. The data obtained were processed by interactive coupling with numerical modelling tools. As it was approved, the key properties of the boundary layer such as temperature and temperature gradient profiles can be analysed in detail and the impact of various factors can be studied. The numerical simulation and the experimental data comparison had shown good coincidence; nevertheless, at a temperature difference of only few degrees, the influence of ambient air movement has to be considered in simulation process. The presented boundary layer analysis can be successfully applied at specific conditions of building physics with the low temperature differences.