RT Journal Article ID 139ba5ab2799e0e0 A1 Singh, Sanjeeva Kumar A1 Verma, Vineet Kumar T1 FLOW IN A COMPOSITE POROUS CYLINDRICAL CHANNEL COVERED WITH A POROUS LAYER OF VARIABLE PERMEABILITY JF Special Topics & Reviews in Porous Media: An International Journal JO STRPM YR 2019 FD 2019-06-27 VO 10 IS 3 SP 291 OP 303 K1 heterogeneous porous medium K1 Brinkman equation K1 modified Bessel function AB In the present article we have considered the steady flow of viscous, incompressible fluid in a composite cylindrical channel. The inner and outer parts of the cylindrical channel is of different permeability. The porous channel consists of two parts. The inner porous cylinder is of uniform permeability k0 which is covered by an outer porous layer of variable permeability. We have considered two cases of permeability variation of the outer porous cylinder: (i) linear variation, k = k0r and (ii) quadratic variation, k = k0r2. An analytical solution of the problem is obtained by using the Brinkman equation. Exact expressions for the velocity, rate of volume flow, average velocity, and shear stress on the impermeable boundary are obtained and exhibited graphically. The effect of permeability variation parameter and the gap parameter on the flow characteristics has been discussed. It is found that these parameters have a very strong effect on the flow. PB Begell House LK https://www.dl.begellhouse.com/journals/3d21681c18f5b5e7,59417f714771369d,139ba5ab2799e0e0.html