Yu. V. Zhukova

Derivation and numerical solution of a system of equations for the single-point probability density and conventional rate of dissipation of turbulent pulsations of a scalar field

On the basis of the authors’ earlier closed equation for the joint probability density function of pulsations of an isotropic turbulent scalar field and its gradient, we derived and solved numerically a system of equations for the single-point probability density and conventional rate of scalar dissipation (CRSD) of fluctuations of a passive scalar field. In closing the equation for the CRSD, the hypothesis that the effect of pulsations of this function on its evolution is of no consequence is adopted. The system includes equations for functions that describe the distribution of turbulent energy and the intensity of scalar pulsations over different length scales.

A closed equation for the joint probability density function of the magnitudes of fluctuations of a turbulent scalar reacting field and its gradient

We derived a closed system of equations for calculating the single-point joint probability density function (JPDF) of the magnitudes of fluctuations of a scalar reacting field and its gradient. The system of equations includes an equation for the JPDF and two equations for functions that describe the distribution of turbulent energy and of the reacting-scalar intensity over various length scales. The latter functions are necessary for calculation of the time-dependent coefficients in the equation for the JPDF.

Drag reduction of energy-efficient buildings and wind energy extraction due to bleeding effect

Turbulent flow around a circular cylinder with a perforated housing, when a stagnation zone flow at the forward stagnation point is transported to the near-wake region during wind energy extraction, was studied numerically using the multiblock computational technologies of solution of the Reynolds equations closed by the equations of the shear stress transfer model. It turned out that the energy extraction promoted an additional drag reduction of the energy-efficient building model under consideration.

Model of the Surface of Equal Concentration in a Turbulent Reacting Flow

Statistical data on the scalar‐field gradient obtained by means of direct numerical simulation of turbulence is used in the present paper to predict the form of the specific area of the isoscalar surface at different stages of evolution of a turbulent flow. From the available literature data on the conditional scalar dissipation rate a suggestion of the form of typical realizations of the turbulent field at different stages of its evolution is made and on this basis the form of the scalar gradient probability density on the isoconcentric surface is proposed. Using this quantity and the idea that the turbulent scalar field is multiscale in nature, it is possible to calculate the dependence of the specific area of equal concentration on the scalar value at the initial, intermediate, and final stages of turbulent mixing. The results of the present work are compared with the results of other theoretical approaches to the calculation of the surface area of equal concentration.

Numerical investigation of the effect of roughness on convective heat transfer under stationary laminar flow of M20 oil around a circular cylinder

Convective heat transfer under the laminar flow (Re = 60) of M20 oil and air heated to 333 K around a circular cylinder with a wavy surface roughness is computed using multiblock computational technologies, which are implemented in code VP2/3 for solving the Navier–Stokes and energy equations as part of the procedure for adjusting pressure. It is shown that at a roughness depth of 1% in fractions of the cylinder diameter, the heat transfer from the surface in oil increases by 21%, and the thermal–hydraulic performance grows by 17%.

Derivation and numerical solution of a closed equation for the specific isoscalar-surface area in a turbulent reactive flow

Based on the equation obtained earlier for the joint probability density function of the fluctuations of an isotropic turbulent scalar field of a reagent and its gradient[Inzh.-Fiz. Zh.,71, No. 5, 827–849 (1998)] the authors derived and numerically solved an equation for the specific isoscalar-surface area Σt(Γ) in a turbulent reactive flow. The equation for Σt(Γ) contains the single-point probability density function for pulsations of a reactive scalar and the time function that depend on the distribution of the energy of turbulent velocity pulsations and the intensity of scalar reagent pulsations by different length scales. The corresponding equations are written for all these functions.