Получение и сравнение расчетных и экспериментальных голографических интерферограмм для описания квази-2D конвективного течения прозрачной газовой смеси

The numerical simulation made in this research serves as a methodological and proof basis for the previously performed experiments on steady-state thermoconcentration convection in gas mixtures of dry air and undecane or water vapor. Experimental data were obtained by two methods: a thermocouple method for quantitative description of the heat flux and holographic interferometry for qualitative visualization of the transparent gas motion (as an alternative to the particle image velocimetry). Convection due to the simultaneous action of vapor concentration and temperature gradients is described by the ratio of the concentration Rayleigh number for the gas mixture and the thermal Rayleigh number for dry air at the same temperature. The quantitative data from thermocouple measurements are interpreted under the assumption of a single-vortex quasi-two-dimensional flow in a rectangular convective cell of dimensions 15х15х320 mm. The aim of the work is to verify and validate the flow of this type by comparing the experimental and calculated interferograms (light refractive index surface) obtained from numerical simulations of thermal convection of dry air. The boundary conditions and geometry of the problem correspond to the experimental conditions. The equations of thermal convection in the Boussinesq approximation are written in the formulation of the two-field approach. The system of differential equations is solved numerically using a grid method by means of a program written in the Python programming language. The experimental interferograms were processed manually in a graphic editor. A direct comparison of about fifty pairs of coinciding experimental and calculated interferograms relating to the same values of temperatures of the heater and cooler of the cell was performed. The comparison of the calculated data and measurements confirmed the correctness of prediction of a single-vortex two-dimensional convective gas flow.