There have been increasing research works in the past few years on analysis of flow of viscoelastic fluid. This is due to its various applications in gaseous diffusion, blood flow through oxygenators, flow in blood capillaries have continue to aroused the research interests. However, complex rheological fluids such as blood, paints, synovial fluid, saliva, jam which cannot be adequately described by Navier Stokes. Consequently, complex constitutive relations that capture the flow behaviour of the complex fluids have been developed.1 Among the newly developed integral and differential-type fluid flow models, Upper convected Maxwell fluid model has showed to be an effective fluid model that captures the complex flow phenomena of fluids especially of the fluid with high elastic behaviours such as polymer melts. Such highly elastic fluids have high Deborah number.2‒3 In the analysis of Maxwell flow, Fetecau4 presented a new exact solution for the flow of fluid through infinite microchannel while Hunt5 studied convective fluid flow through rectangular duct. Sheikholeslami et al.6 investigated magneto hydrodynamic field effect on flow through semi-porous channel utilizing analytical methods. Shortly after, Sheikholeslami7‒9 adopted numerical solutions in the investigations of nanofluid in semi-annulus enclosure.
Flow of upper convected Maxwell fluid through porous stretch sheet was investigated by Raftari & Yildirim.10 Entophy generation in fluid in the presence of magnetic field was analyzed by Sheikholeslami & Ganji11 using lattice Boltzmann method while Ganji et al.12 explored analytical and numerical methods to analyze the fluid flow problems under the influence of magnetic field. The flow of viscoelastic fluid through a moving plate was analyzed by Sadeghy & Sharifi13 using local similarity solutions. Vajrevulu et al.14 investigated the mass transfer and flow of chemically reactive upper convected Maxwell fluid under induced magnetic field. Not long after Raftari & Vajrevulu15 adopted the homotopy analysis method in the study of flow and heat transfer in stretching wall channels considering MHD. Hatami et al.16 presented forced convective MHD nanofluid flow conveyed through horizontal parallel plates. Laminar thermal boundary flow layer over flat plate considering convective fluid surface was analyzed by Aziz17 using similarity solution. Beg & Makinde18 examined the flow of viscoelastic fluid through Darcian microchannel with high permeability.
Most of the above reviews studies focused on the analysis of fluid flow under no slip condition. However, such an assumption of no slip condition does not hold in a flow system with small size characteristics size or low flow pressure. The pioneer work of flow with slip boundary condition was first initiated by Navier.19 The slip conditions occur in various flows such as nanofluids, polymeric liquids, fluids containing concentrated suspensions, flow on multiple interfaces, thin film problems and rarefied fluid problems.19‒31 Due to the practical implications of the condition on the flow processes, several studies on the effects of slip boundary conditions on fluids flow behaviours have been presented by many researchers.19‒35 Abbasi et al.36 investigated the MHD flow characteristics of upper-convected Maxwell viscoelastic flow in a permeable channel under slip conditions. However, an analytical study on simultaneous effects of slip, magnetic field, nanoparticle and porous medium on the flow characteristics of an upper-convected Maxwell viscoelastic nanofluid has not been carried out in literature. Therefore, in this work, homotopy perturbation method is used to analyze the slip flow of an upper-convected Maxwell viscoelastic nanofluid through a permeable microchannel embedded in porous medium under the influence of magnetic field is analyzed. Also, the effects of other pertinent parameters of the flow process are investigated and discussed.
Consider a laminar slip flow of an electrically conducting fluid in a microchannel is considered. Along the y axis, magnetic fields are imposed uniformly, as described in the physical model diagram Figure 1. It is assumed external electric field is zero and constant of electrical conductivity is constant. Therefore, magnetic Reynolds number is small and magnetic field induced by fluid motion is negligible.
Figure 1 Flow of upper-convected Maxwell fluid between in permeable channel embedded in porous medium.
Based on the assumptions, the governing equation for the Maxwell fluid is presented as8
(1)
where the Cauchy stress tensor is T and S is the extra-stress Tensor which satisfies
(2)
The Rivlin-Ericksen tensor is defined by
(3)
The continuity and momentum equations for steady, incompressible two dimensional flows are expressed in Eqs. (4) -(6) as
(4)
(5)
(6)
where the effective density and effective dynamic viscosity of the nanofluid are defined as follows:
and
Sxx,Sxy,Syx and Syy are extra stress tensors and ρ is the density of the fluid. Using the shear-stress strain for a upper-convected liquid, The governing equations of fluid motion is easily expressed as16
(7)
(8)
where flow velocity component (u,v) are velocity component along the x and y directions respectively. Since flow is symmetric about channel center line, attention is given to the flow region 0<y<H. Appropriate boundary conditions are given as
(9)
(10)
where Vw and β are the wall characteristic suction velocity and sliding friction respectively.
The physical and thermal properties of the base fluid and nanoparticles are given in Table 1 and Table 2, respectively.
Base fluid |
ρ(kg/m3) |
Cp (J/kgK) |
k(W/mK) |
σ(Ω-1m-1) |
Pure water |
997.1 |
4179 |
0.613 |
5.5 |
Ethylene Glycol |
1115 |
2430 |
0.253 |
1.07 |
Engine oil |
884 |
1910 |
0.144 |
4.02 |
Kerosene |
783 |
2010 |
0.145 |
4.01 |
Table 1 Physical and thermal properties of the base fluid
Nanoparticles |
ρ(kg/m3) |
Cp(J/kgK) |
k(W/mK) |
σ(Ω-1m-1) |
Copper (Cu) |
8933 |
385 |
401 |
59.6 |
Aluminum oxide (Al2O3) |
3970 |
765 |
40 |
16.7 |
SWCNTs |
2600 |
42.5 |
6600 |
1.26 |
Silver (Ag) |
10500 |
235 |
429 |
|
Titanium dioxide (TiO2) |
4250 |
686.2 |
8.9538 |
|
Copper (II) Oxide (CuO) |
783 |
540 |
18 |
|
Table 2 Physical and thermal properties of nanoparticles
The similarity variables are introduced as:
(11)
With the aid of the dimensionless parameters in Eq. (11), the constitutive relation is satisfied. Equation (2-4) can be expressed as:
(12)
Taking boundary condition as
(13)
where
is the Reynolds number,
is the Deborah’s number,
is the Hartman parameter,
is the Darcy’s number. For Rew>0 corresponds to suction flow while Rew<0 correspond to injection flow respectively.
Equ. (13) is a third-order differential equation with four boundary conditions. Through a creative differentiation of Eq. (12). Hence introducing fourth order equation as:
(14)
The above Eq. (14) study satisfies all the four boundary conditions
Principles of homotopy perturbation method
The following equation is considered in explaining the fundamentals of the homotopy perturbation method [10]
(15)
Utilizing the boundary condition
(16)
A is the general differential operator, B is the boundary operator, f(r) is the analytical function and Γ is the boundary domain of Ω. Separating A into two components of linear and nonlinear terms L and N respectively. The Eq. (21) is reconstructed as
(17)
Homotopy perturbation structure takes the form
(18)
Where
(19)
p ϵ(0, 1) is the embedding parameter and U0 is taken as the initial term that satisfies boundary condition. The power series of Eq. (24) can be expressed as:
(20)
Most appropriate solution for the problem takes the form
(21)
Application of the homotopy perturbation method to the flow problem
The homotopy pertubation method which is an analytical scheme for providing approximate solutions to the ordinary differential equations, is adopted in generating solutions to the coupled ordinary nonlinear differential e quation .Upon constructing the homotopy, the Eqs. (11)- (12) can be expressed as
(22)
Taking power series of velocity and rotation fields yields
(23)
Substituting Eq. (23) into (22) and collecting the like terms of the various order yields
(24)
(25)
(26)
The boundary conditions are
(27)
On solving Eq. (24) applying the boundary conditions yields
(26)
Also, solving Eq. (25) applying the corresponding boundary conditions yields
(27)
By the definition of homotopy perturbation method, we have
(28)
In this work, homotopy perturbation method is used to analyze the flow of an upper convective Maxwell (UCM) nanofluid through a permeable microchannel embedded in a porous medium and under the influence of slip condition has been presented. Important fluid parameter effect such as Deborah’s number, Darcy parameter and Hartman parameter on the fluid flow was investigated. that increase in slip parameter, nanoparticle concentration and Darcy number lead to increase in the velocity of the upper-convected Maxwell fluid while increase in Deborah’s, Hartmann and Reynold numbers decrease the fluid flow velocity towards the lower plate but as the upper plate is approached, a reverse trend is observed. The results obtained in this work can be used to further the applications of UCM fluid in biomedical, astrophysics, geosciences etc.
Reynolds number
M Hartman parameter
K Slip parameter
De Deborah’s number
HAM Homotopy analysis method
Auxilliary parameter
y axis velocity component
x axis velocity component
Dimensionless horizontal coordinate
Dimensionless vertical coordinate
Distance in x axis parallel to plate
Distance in y axis parallel to plate
Da Darcy number