International Journal of Engineering Trends and Technology (IJETT) – Volume 14 Number 2 – Aug 2014 Numerical Modeling of Couette Flow Problem With Suspended Particulate Matter Pramodini Samal 1 , T.C.Panda 1 2 2 Orissa Engineering College, Bhubaneswar-751007 (Odisha), India. Department of Mathematics, Berhampur University, Berhampur-760007 (Odisha), India. Abstract: The solution of the governing equations of incompressible Couette flow with suspended particulate matter is obtained by using finite difference technique with non uniform grid. Starting from the assumed initial conditions the velocity and temperature distribution are computed in steps of time .It is observed that the velocity and temperature are changing rapidly near upper plate as to be expected. It has been observed that the final steady state profiles are linear for clear fluid where as it is not linear in case of fluid with particulate matter. The effect of particle loading is to decrease the velocity and temperature of the carrier fluid. Keywords: Suspended Particulate Matter, Particle Loading, Volume Fraction, Diffusion, Viscocity, Nomenclature: C , C → Specific heats of fluid and solid particles Ec → Eckert numbe F → dust parameter h → distance between plates k → thermal conductivity Pr →prandtl number Re → fluid phase Reynolds number t → time t ∗ →dimensionless time ( T,T ,) → Temperature of fluid and particle phase T → Temperature of the plate at η = 0 T → Temperature of the plate at η = 1 (u∗ ,u∗ ) → non-dimensional velocity components of fluid and particle phase respectively (u, v) → fluid phase velocities (u , v )→ particle phase velocities (x, y) → space co-ordinates D → diffusion parameter U → velocity of the upper plate α → Particle loading ε = → diffusion parameter ISSN: 2231-5381 (ν, ν ) → kinetic coefficients of viscosity of fluid and particle phase respectively (ρ, ρ ) → density of fluid and particle phase respectively ρ∗ → dimensionless density of the particle phase γ → ratio between C and C φ → volume fraction of the suspended particles I. INTRODUCTION The study of transport phenomena i.e transfer of mass, momentum and energy is increasingly recognized as a unified description of fundamental importance. The mean velocity does not only describe the transport of substances but also by the presence of random chaotic fluctuations in the velocity field. For calculating adjective transport of substances, data on the vector field of mean current velocity for the ocean region are needed with variation of time. The prediction of the mechanical transport in the ocean is a difficult task. Parallel flow through a straight channel provides a good understanding in connection with flow in estuaries. With a view to study the transport through estuaries, we have considered a simple case of flow situation between two infinite parallel plates. Malashetty M.S et al [4] have studied two phase MHD flow and heat transfer in an inclined channel in which one phase is electrically conducting and it has been found that the velocity and temperature can be increased or decreased with suitable values of the ratios of viscosities, thermal conductivities, the heights and the angle of inclination. http://www.ijettjournal.org Page 81 International Journal of Engineering Trends and Technology (IJETT) – Volume 14 Number 2 – Aug 2014 Seth et a;[12] have studied combined free and forced convention flow of a viscous incompressible electrically conducting fluid in a rotating channel and obtained an analytical solution in closed form and derived the effect of grashof number and rate of heat transfer at both the plates. XUJ.L et al[14] have investigated experimentally an adiabatic concurrent vertical two phase flow of air and water in vertical rectangular channels and compare a model which has been extended to predict the flow regime transition from bubbly flow to slug flow, slug flow to churn flow using the bubble rising velocity and the increased frictional co-efficient for rectangular channels. ZangLian et al [15] have developed single and multichannel experimental structures using plasma-etched silicon with Pyrex glass cover, which allow uniform heating and spatially resolved thermometry and provide optical access for visualization of being regimes and found pressure drop and wall temperature distribution data, which are consistent with predictions accounting for solid conduction and homogeneous two-phase convection. Lain.Santiogo et al [3] have studied detailed measurements in a horizontal channel flow laden with solid particles with different size and loading ratio using phase-Doppler anemometry. They validated the numerical calculations based on the Euler/Lagrange approach. The conservation equation includes appropriate source term resulting from the dispersed phase. For modeling the particle phase in the Lagrangian frame all relevant effects are accounted for such as transverse lift forces, wall collisions with roughness and interparticle collision. Muste.M et.al [6 ] have studied the comparison of two phase flow with the traditional mixed flow essentially as flow of a single fluid. They confirmed that suspended particles may affect a turbulent flow throughout its depth. Suspended particles modify flow turbulence, the main effects quantified being decreases in the bulk water velocity and in the Von Karman constant, while the flows friction velocity remains approximately constant. Rohimzadeh etal [8] have studied the large eddy simulation method (LES) which was used for simulating the particle laden turbulent flow. It is ISSN: 2231-5381 concluded in the model that the presence of particles has negligible effect on the carrier flow. WEI,Zhangying et al [13] have investigated the particle flow of water mixed with sand escaped from filtering in the labyrinth channel.CFD analysis has been performed on liquid solid two phase flow in labyrinth channel emitters so CFD analysis can be used in optimal design of labyrinth-channel emitters. There have been several investigations of Couette flow.H.Schlichting [11] has given the solutions to those problems for an incompressible Newtonian fluid. Data and Mishra [2] have studied unsteady Couette flow and heat transfer of a dusty fluid filling the gap between two infinite parallel plates kept at arbitrary temperature and found the solution to be valid for any time.Panda , Mishra & Panda [8] have studied the unsteady Couette flow and heat transfer of a dusty fluid with the inclusion of volume fraction and Brownian diffusion of SPM in the mathematicalformulation.They have obtained the solution by using Cranck-Nicholson finite implicit scheme. In the present study the finite volume fraction, Brownian diffusion of SPM are considered to show the effect on unsteady two phase coquette flow with heat and mass transfer. Schematic of Couette Flow II. MATHEMATICAL MODELING Consider the two phase flow between two parallel plates separated by a vertical distance L. The upper plate is moving at the velocity U and the lower plate http://www.ijettjournal.org Page 82 International Journal of Engineering Trends and Technology (IJETT) – Volume 14 Number 2 – Aug 2014 is kept stationary. The flow field between the two plates is driven exclusively by the shear stress exerted on the fluid by the moving upper plate resulting in a velocity profile across the flow. Let the lower plate be coincident with the plane y=0 and upper plate be placed at the plane y=L , the lower plate is held at a constant temperature and upper plate at . The basic equations for the present investigation are based on the balance laws of mass, linear momentum and energy for both phases which are viewed as interacting continua. In the present work the hydrodynamic interaction of the particles and the fluid is restricted to a mutual drug force (based on Stroke’s linear drag theory). Whose value depends on the particle concentration and the relative velocity between the phases. Since the particle phase Reynolds number is assumed to be small, other interaction forces such as the virtual mass force, the shear lift force (Saffiman[ 10 ]) and the spin lift force(Rubinow and Keller [ 9 ]) are negligible compared to the Stoke’s drag force. The Thermal interaction between the phases is limited to energy transfer or heat flux due to temperature difference between the particles and the fluid. This depends on the ratio of the velocity relaxation time to the temperature relaxation time (marble [5]).No radioactive heat transfer from one particle to another and from mutual particle interaction is assumed to exist since the fluid acts as a buffer which prevents direct contacts between the surfaces of different particles. Models of this type have been given previously by many investigators such as Marble [ 5] and Chamakha [1 ] Here the model for Couette flow stretches from +∞ to−∞ in x-direction. Science there is no beginning or end of this flow, the flow field variables must be independent of x. In the present problem the equation of continuity for fluid phase is given by ( ) If we expand V in Taylor Series about the point y=0, we get ( ) = (0) + + 2 (ℎ) = (0) + +… … … .. = ℎ, we get Evaluating at the upper plate at ℎ +… … … .. 2 ℎ+ Since (0) = 0, (ℎ) = 0, 0……….. = =0 = 0 Implies ℎ . This is a physical characteristic of Coutte flow, namely that there is no vertical component of velocity anywhere. This leads us to assume ≈ 0 in accordance with the physical characteristic of Coutteflow. From particle phase continuity equation, we get + ≈ 0,gives, Thus (1 − ) =0 = constant everywhere = (1 − ) + (1 − ) − − − − − (1) (2) = (1 − ) + (1 − ) + (3) =0 =− ( ) =0 = 0 Or = ( ) = 0. i.e = 0 As at the lower plate = 0 + ISSN: 2231-5381 ( ) − + (4) =0 http://www.ijettjournal.org Page 83 International Journal of Engineering Trends and Technology (IJETT) – Volume 14 Number 2 – Aug 2014 Introducing the non-dimensional variables ∗ = ∗ , ∗ , = , ∗ , = ∗ , = ∗ , = = −2 , = , − = , = , = ( ) = , 1 1− + , (5) ∗ = And after dropping stars the equations (5.1) to (5.4) reduces to ∗ , ∗ – 1.5 , = + 0.5 = , = = = = Where = −2 = − − + − (7) , = + − − =− ∗ − 1.5 , ( − ) − − ∗∗ − Pr + − = 0, − 1− 4 1 31 − − >0 = 1 = 0as impermeable. = ( >0 the plates = METHOD OF SOLUTION By the method of Finite difference Technique using Non Uniform grid, equations (6) to (9) are reduced to the following form + ∗ , ∗∗ + + + ∗ + ∗∗ = , + ∗ + ∗∗ + ISSN: 2231-5381 , = = = 1 ∗ ∗∗ (12) (13) (14) ∆ + 2 1 31 − 1 1 1− ( ) − = −1.5 − , ∆ + − 1− 3 Pr 2 ( ) , = − +1 2 3 Pr 2 − +1 + +1 −2 IV. (11) + − ) are (10) III. − +1 ≤0 = 0 = 1, = 0, < 1 + 0.5 − + = −1.5 − ∗∗ = −2 = 0 0 ≤ = 1, ∆ The boundary conditions for the present problem are = 0, −2 ∗∗ , = (9) = + = + 0.5 = (8) − −2 (6) ∗∗ = − ∆ − = 2 + 0.5 − ∆ RESULT ANALYSIS Some results for the velocity and temperature profile at various stages in the time marching process are shown in fig 1,2, 3, 4.The initial condition in the figure is labeled as 0.∆ .The velocity and temperature profile after 2 times steps is labeled 2.∆ . Clearly the velocity and temperature are http://www.ijettjournal.org Page 84 International Journal of Engineering Trends and Technology (IJETT) – Volume 14 Number 2 – Aug 2014 changing most rapidly near the upper plate as expected .Other profiles are shown after 12.∆ , 36.∆ , 60.∆ , 240.∆ respectively. The driving influence of the shear stress exerted by the upper plate is gradually communicated to the rest of the fluid, resulting in a final, steady state profile after 240 time steps after u. This steady state profile is linear, as expected and perfectly agreed with exact, analytical solution .It is also observed that the steady state for u with SPM (∝= 0.1) is reached after 240 time steps. Thus it is concluded that the presence of particles have no effects for the carrier fluid velocity to reach it’s steady state (Fig-1). From Fig-2 , it can be concluded that the steady state achieved after 36 time steps (∝= 0) and also when presence of particles (∝= 0.1) Fig-2 Fig-3 depicts the particle phase velocity for different time steps. The steady state profile for is reached after 240 time steps and the steady state profile is linear. But the steady state profile for is reached after 36 time steps (Fig-4) but it is not linear. 1.20E+00 1.00E+00 T(0) 8.00E-01 T(2) 6.00E-01 T(36) 4.00E-01 T(120) 2.00E-01 T(240) 0.00E+00 -2.00E-01 0 0.5 Fig-2 Variation of U with Y 1 1.5 (α = 0.1) 1.20E+00 1.00E+00 UP(0) 8.00E-01 UP(2) 6.00E-01 UP(36) 4.00E-01 UP(120) 2.00E-01 The above calculations we have carried out with E=1. Since there is no difference in the behavior of the solution for larger value of E . However for large E, number of steps for attending steady state may require more marching steps to attain steady state. Variation of U with Y (α = 0) i.e. Clear fluid 0.00E+00 -2.00E-01 1.00E+00 8.00E-01 8.00E-01 U(0) 6.00E-01 6.00E-01 U(2) 4.00E-01 4.00E-01 U(36) 2.00E-01 2.00E-01 U(12 0) 0.00E+00 0.00E+00 0.5 1 0.5 1 1.5 1.20E+00 1.00E+00 0 0 Fig-3 Variation of T with Y (α = 0.1) 1.20E+00 -2.00E-01 UP(240) TP(2) TP(36) -2.00E-01 1.5 TP(0) TP(120) TP(240) 0 0.5 1 1.5 Fig-4 Fig-1 Variation of Temperature with Y (α = 0.1) ISSN: 2231-5381 http://www.ijettjournal.org Page 85 International Journal of Engineering Trends and Technology (IJETT) – Volume 14 Number 2 – Aug 2014 [9] BIBLIOGRAPHY [1] Chamkha A.J. & Peddieson J. Jr. [1994], “Boundary layer theory for a particulate suspension”, J. of Fluids Engineering, March 116:147-153. [2] Datta N. & Mishra S.K. [1983], “Unsteady couette flow and heat transfer in a dusty gas”, Int. comm. Heat Mass Transfer, 10:153-162. [3] Lain S., So mmerfeld M. & K ussin J. 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