A numerical model is used to study the effect of the height and position of an overflow sill on glass melt hydrodynamics and heat transfer in a glass-melting tank furnace. A differentiated effect of the overflow sill on the formation of convection flows and heat and mass transfer in various parts of the tank is established. It is demonstrated that the considered parameters of the sill have virtually no effect on the intensity of the charge convection cycle. At the same time, they have a significant effect on melt hydrodynamics past the sill. The quantitative correlations between the design parameters of the sill and certain characteristics of heat and mass transfer in the melting tank are identified.An overflow sill in the melting tank is an obligatory element of contemporary glass-melting furnaces. Physical modeling of melting tank hydrodynamics has provided a qualitative understanding of its role in convection flows [1,2]. At the same time, it should be noted that the limitations of this method do not provide reliable quantitative information needed for design work. The quantitative regularities of the effect of this structural element on the melt flow pattern and temperature field can be obtained using contemporary computer simulation technologies, for instance a numerical model of melting tank hydrodynamics [3,4]. Computations have been performed for the following linear sizes of the melting tank (m): L mt = 13.62, h 1 = 1.3, h n = 0.3, and b s = 0.4 (Fig. 1) The overflow sill height h s was taken equal to 0.2, 0.4, 0.6, 0.8, 1.0, and 1.1. m. The longitudinal coordinate of the sill remained constant for all variants: x s = 9.2 m. The location of the sill along the melting tank varied within the limits of x s /L mt = 0.44 -0.91 (x s = 6.0 -12.4 m) with a step of 0.4 m; the sill height remained constant, h s = 0.8 m. Other initial data and boundary conditions for modeling are specified in [4 -6].The results of numerical modeling are represented by two-dimensional fields of relative streamlines and glass melt temperatures. Streamlines are normalized with respect to the mass flow rate of glass through the tank neck equal to 3.47 kg/sec. For a clear representation of flow patterns in different parts of the tank, the scale variation method was applied. The furnace output of 300 tons/day accepted in the computations is achieved by a specific glass melt output equal to 2.6 tons/m 2 per day. The glass melt temperature distribution t gm on the tank surface is specified by the regression equation obtained on the condition that the total flame length l f -L mt (the length of the visible part of the flame is 0.7L mt , i.e., x = 9.534 m) [7]: t gm (x, y ) = 1145.23 + 87.11x + 32.76y -19.51x 2 -1.24xy -12.96y 2 + 0.13x 2 y + 0.18xy 2 -0.02x 2 y 2 + 2.55x 3 + 1.95y 3 -0.11x 4 -0.10y 4 , where x and y are the longitudinal and lateral coordinates of the tank, m.In two-dimensional setting the temperature distribution on the glass melt surface is specified by the expression obtained by averaging the following equation across the...