UDC 621 SLOW FLOW PAST A SWARM OF CYLINDRICAL PARTICLES WITH SURFACTANT LAYER COATING © Shweta Raturi Graphic Era Hill University, Dehradun, India Sunil Datta LucknowUniversity, Lucknow, India Abstract. <...> The present study examines the analytical solution of slow viscous flow past a swarm of cylindrical particles, where each particle consists of a solid core covered by a liquid shell coated with monomolecular layer of the surfactant layer using cell model. <...> We have assumed that each particle is enclosed by a hypothetical cell. <...> The boundary conditions of Happel’s, Kuwabara’s, Kvashin’s and Cunningham (usually referred to as Mehta-Morse’s) are considered on hypothetical cell. <...> The effects of surfactants are accommodated by considering the Scriven’s boundary conditions at the shell involving surface tension, surface shear viscosity and surface dilatational viscosity. <...> The drag force on the cylindrical particle in a cell is evaluated. <...> The variation of drag force with various parameters is graphically presented. <...> Keywords: cell model, surface dilatational viscosity, surface shear viscosity and surface tension. <...> Forces, now acting on the interface, are surface tension gradients and the viscous resistance to shear and dilatation. <...> When the surfactant monomolecular layer of fluid is present at the interface, the boundary conditions at the free surface or at an interface get altered due to the presence of surface layer parameters (surface dilatational viscosity), ε (surface shear viscosity) and σ (surface tension). <...> The surfactants are insoluble in both bulk phases, and the interface obeys a linear rheological model given by Boussinesq [1] and generalized by Scriven [2] constitutive law. <...> The motion of liquid drops and gas bubbles in the presence of surfactants is of major importance because of its significance in a variety of applications, such as nuclear physics, meteorology and chemical engineering. <...> The earliest investigations of the motion of a liquid drop in another immiscible liquid were carried out by Rybezynski [3] and independently by Hadmard [4]. <...> Later on the dynamics of fluid interfaces were investigated by Lamb [5], Reid [6], Miller and Scriven [7], Ramabhadran et al., [8] and Prosperetti [9, 10]. <...> The motion of a spherical bubble rising steadily in dilute surfactant solutions has been investigated by Harper [11, 12, 13 <...>