Entropy Generation Optimization in Squeezing Magnetohydrodynamics Flow of Casson Nanofluid with Viscous Dissipation and Joule Heating Effect

In this research article, the investigation of the three-dimensional Casson nanofluid flow in two rotating parallel plates has been presented. The nanofluid has been considered in steady state. The rotating plates have been considered porous. The heat equation is considered to study the magnetic field, joule heating, and viscous dissipation impacts. The nonlinear ordinary system of equations has been solved analytically and numerically. For skin friction and Nusslt number, numerical results are tabulated. It is found that velocity declines for higher values of magnetic and porosity parameter while it is heightened through squeezing parameter. Temperature is an enhancing function for Eckert number and nanoparticles volume fraction. Entropy generation is augmented with radiation parameter, Prandtl, and Eckert numbers. The Casson, porosity, magnetic field, and rotation parameters were reduced while the squeezing and suction parameters increased the velocity profile along x-direction. The porosity parameter increased the Bejan number while the Eckert and Prandtl numbers decreased the Bejan number. Skin friction was enhanced with increasing the Casson, porosity, and magnetic parameters while it decreased with enhancing rotation and squeezing parameters. All these impacts have been shown via graphs. The influences by fluid flow parameters over skin friction and Nusselt number are accessible through tables.


Introduction
In the modern world of science and technology, we need more development in the direction of the exhaustion of energy in engineering and industrial fields. Thus, for the exhaustion and transfer of heat, Alain Portavoce et al. [38] explored transmission of atom in crystalline thin film. Oudina [39] explored heat transfer in Titania nanofluids in cylindrical annulus with discontinuous heat source. Oudina [40] studded MHD flow with natural convection between vertical coaxial cylinders. Reza et al. [41] explored nanofluids flow with MHD in a narrow channel with stretching walls. Jawad et al. [42] explored the MHD flow between two plates with different angle. Alkasassbeh et al. [43] investigated heat transfer by the fin attached to hybrid generator. Salim et al. [44] analyzed MHD jaffery suction flow through homotopy analysis method. Batti et al. [45] explored entropy production with MHD in nanofluid flow via porous stretching plate. Rashidi et al. [46] explored the entropy production in a single-slope solar still. Batti et al. [47] explored entropy production in entropy production with MHD during thermal radiation past a shrinking surface. Esfahani et al. [48] explored entropy production in nanofluid flow streaming past a wavy wall. For more study on entropy analysis, see [49][50][51][52][53][54][55][56][57].
In this research article, the investigation of the three-dimensional Casson nanofluid flow in two rotating parallel plates has been presented. The nanofluid has been considered in a steady state. The rotating plates have been considered porous. The heat equation is considered to study the magnetic field, joule heating, and viscous dissipation impacts. The nonlinear ordinary system of equations has been solved analytically.

Problem Formulation
Here, we assumed 3D unsteady flow of Casson nanofluid to have viscous dissipation, joule heating, and entropy generation properties in two rotating parallel plates. Both plates are permeable. where a and s are the stretching and time parameters. The whole system rotates with angular velocity Ω 0 . The lower plate temperature is denoted by T w and the upper plate temperature is denoted by T h . It is also supposed that T w > T h . Figure 1 shows the symmetric flow sketch of the nanofluids. dissipation. Kumam et al. [37] studied the MHD nanofluid flow in rotating channels with entropy generation. Alain Portavoce et al. [38] explored transmission of atom in crystalline thin film. Oudina [39] explored heat transfer in Titania nanofluids in cylindrical annulus with discontinuous heat source. Oudina [40] studded MHD flow with natural convection between vertical coaxial cylinders. Reza et al. [41] explored nanofluids flow with MHD in a narrow channel with stretching walls. Jawad et al. [42] explored the MHD flow between two plates with different angle. Alkasassbeh et al. [43] investigated heat transfer by the fin attached to hybrid generator. Salim et al. [44] analyzed MHD jaffery suction flow through homotopy analysis method. Batti et al. [45] explored entropy production with MHD in nanofluid flow via porous stretching plate. Rashidi et al. [46] explored the entropy production in a single-slope solar still. Batti et al. [47] explored entropy production in entropy production with MHD during thermal radiation past a shrinking surface. Esfahani et al. [48] explored entropy production in nanofluid flow streaming past a wavy wall. For more study on entropy analysis, see [49][50][51][52][53][54][55][56][57].
In this research article, the investigation of the three-dimensional Casson nanofluid flow in two rotating parallel plates has been presented. The nanofluid has been considered in a steady state. The rotating plates have been considered porous. The heat equation is considered to study the magnetic field, joule heating, and viscous dissipation impacts. The nonlinear ordinary system of equations has been solved analytically.

Problem Formulation
Here, we assumed 3D unsteady flow of Casson nanofluid to have viscous dissipation, joule heating, and entropy generation properties in two rotating parallel plates. Both plates are permeable. The suction velocity of the fluid via upper porous plate is 0 V . The magnetic field's strength  Figure 1 shows the symmetric flow sketch of the nanofluids.  Nanofluid flow governing equations are [53][54][55][56]: ∂v ∂t Problem constrains at the boundary is of the form: The applied two forces are equal in measurement but reverse in direction, keeping the plates stretched. The lower plate is extended because of these equivalent forces in size and inverted direction, while the lower plate is squeezed down with velocity V h (t). u = U w = ax 1−st Illustrates the stretching velocity at y = 0 while u = 0 illustrates the free stream velocity at y = h(t). At the surface of the lower plate, there is a suction represented by v = − V o 1−st while at y = h(t) there is a squeezing velocity represented by v = − s 2 υ n f a(1−st) . T = T w and T = T h characterize the constant temperature at the lower plate and rise of mercury at upper plate at y = 0 and y = h(t), respectively. In the above equations u, v and w are the velocity components in their respective directions. κ * demonstrates the absorption coefficient or porosity of the medium and Ω 0 define the angular velocity. Furthermore, µ n f describes the nanofluid viscosity, ρ n f describes the nanofluid density, κ n f defines the nanofluid thermal conductivity, and (C p ) n f illustrates the nanofluid specific heat capacity, which are defined as where Φ, µ f , ρ f , κ f , σ f , (C p ) f , s, f , and n f indicate the nanoparticle volume fraction, dynamic viscosity, density, thermal conductivity, electric conductivity, specific heat capacity, solid nanoparticles, base fluid, and nano-fluid, respectively. The transformation variables are demarcated: Obviously, Equation (1) satisfies, and Equations (2)-(6) becomes: Pr Satisfying the succeeding boundary conditions: Here the following ratios are defined between the nanofluid and base fluid.
shows the Prandtl number, are local Eckert numbers. The skin friction and Nusselt number of the nanofluid can be characterized as: where τ w defines wall share stress and q w defines heat flux. Mathematically, we have: Substituting Equation (14) in Equation (13), in a simple way, is where Re x = xU w υ f defines the Reynolds number.

Entropy Analysis
The rate of entropy production (E G ) is obtained as [47,48]: Using Equations (8) and (16) reduced as: where The entropy generation rate is reduced as: In components form, Equation (18) is expressed as: The complete volumetric entropy production is demarcated as: The non-dimensional total entropy generation is reduced as:

Bejan Number
The Bejan number shows the quotient of entropy production rate for heat transfer to entire entropy production. It is characterized as: The Bejan number permanently lies in the range of 0 and 1. The Nh falls down in the region 0 ≤ Be < 1 2 . The N f + N j + Np dominates in the region 0.5 < Be ≤ 1.0. For Be = 0.5 in cooperation, the properties are balanced.

HAM Convergence
When we compute the series solutions of the velocity and temperature functions in order to use HAM, the assisting parameters f ,g,θ appear. These assisting parameters are responsible for adjusting the convergence of these solutions. The combined − curve of f (0), g (0) and θ(0) at 10th-order approximations are plotted in Figure 2 for different values of the embedding parameter. The combined − curve consecutively displays the valid region.

Results and Discussion
This segment treaties with the physical impacts of concerned factors of the nanofluid flow on velocity profiles
The impact of Casson parameter β o is depicted in Figure 3a,b. The growing Casson parameter declines the velocity profiles ( f (ξ), f (ξ)) of the nanofluid flow. Actually, the upsurge in Casson parameter β o escalates the plastics dynamic viscosity of the nanofluid, which creates resistance during the flow of nanofluid and decline in the velocity profile occurs. The same impact can be seen in Figure 3b at 0.0 ≤ ξ < 0.45. In this figure, the velocity profile increases at 0.45 < ξ ≤ 1.0 because of the extending of the lower plate. The impact of porosity parameter λ is depicted in Figure 4a,b. Physically, the porous media acts on the boundary layer flow, which produces the opposition to the fluid's flow and thus fluid's velocity declines. This impact is shown in Figure 4a. Similarly, the porosity  Figure 4b. This impact is because of the extending of the lower plate. The impact of squeezing parameter β is portrayed in Figure 5a,b. The escalation in β upsurges the velocity profiles. Physically, the higher values of β move the upper surface descending and additional pressure utilized over fluid's particles. Therefore, the velocity profiles increased. Figure 6a,b displays the result of M on velocity profiles. Actually, the Lorentz force declares that the induced M resists the fluid motion on the liquid boundary, which as a result, diminishes the velocity of the liquid. The impression of δ on velocity profiles is illustrated in Figure 7a,b. The higher values of δ upturns the velocity along x-direction while the greater values of δ reduce the velocity in y-direction. The impression of rotation α is depicted in Figure 8a,b. Clearly, from Figure 8a, the increase in α reduces the velocity profile in x-direction. From Figure 8b, the velocity profile reduces in y-direction at 0.0 ≤ ξ < 0.40 while it increases at 0.4 ≤ ξ ≤ 1.0. The impression of Ec on θ(ξ) is offered in Figure 9. The increasing Ec upsurges the fluid flow temperature. Actually, the Eckert number produces viscous resistance due to the occurrence of dissipation term, which increases the nanofluid thermal conductivity to upsurge the temperature field. A similar impact can be seen in Figure 10. The influence of squeezing β on θ(ξ) is depicted in Figure 11. Unmistakably, we saw that the temperature increases rapidly with the enlargement in β. Bigger β implies that the upper plate moves in a descending fashion in consequence with the fluid interatomic collision increments because of the little space accessible concerning the plates to the nanofluid particles. At the point when the impacts among the atoms of the nanofluid improve, the nanofluid temperature upsurges. Figure 12 exhibits the impression of Pr on θ(ξ). Here, we analyzed that temperature field diminishes by means of escalation in Pr. Bigger estimations of Pr connects to lesser heat conductivity, hence the temperature profile is diminished. Figure 13a illustrates the impression of Pr on Ns(ξ). The value of Pr escalates the entropy generation. The magnetic field boosts the form of the plate surface to its maximum values in the area of the plate. The opposite impact of Prandtl number Pr on Be(ξ) is demonstrated in Figure 1. Figure 14a,b denotes the effect of porosity parameter λ over Ns(ξ) and Be(ξ). Both the entropy and Bejan number boost with the escalation in porous media. It is perceived that the entropy upsurges more speedily compared to Bejan number. Figure 15a,b demonstrates the impact of Eckert number Ec over Ns(ξ) and Be(ξ). The escalation in Eckert number upsurges the entropy generation Ns(ξ) while it diminishes the Be(ξ). Similar impacts of Ed on Ns(ξ) and Be(ξ) are observed in Figure 16a,b.
The impressions of Casson parameter β o , magnetic field M, rotation parameter α, squeezing parameter β, suction parameter δ, porosity parameter λ, Prandtl number Pr, and local Eckert numbers {Ec, Ed} over skin friction C f x and Nusselt number Nu x are displayed in Tables 1 and 2, respectively. The escalating approximations of squeezing and rotation parameters reduced the C f x while the rise in Casson, porosity, and magnetic field parameters augmented the C f x . The rising approximations of squeezing parameter showed dual behavior in Nu x . The escalating approximations of Prandtl number, Eckert numbers, and magnetic field parameter declined the Nu x .
Entropy 2019, 21, x FOR PEER REVIEW 9 of 18 Figure 9. The increasing Ec upsurges the fluid flow temperature. Actually, the Eckert number produces viscous resistance due to the occurrence of dissipation term, which increases the nanofluid thermal conductivity to upsurge the temperature field. A similar impact can be seen in Figure 10. The influence of squeezing β on ( ) θ ξ is depicted in Figure 11. Unmistakably, we saw that the temperature increases rapidly with the enlargement in β . Bigger β implies that the upper plate moves in a descending fashion in consequence with the fluid interatomic collision increments because of the little space accessible concerning the plates to the nanofluid particles. At the point when the impacts among the atoms of the nanofluid improve, the nanofluid temperature upsurges. Figure 12 exhibits the impression of Pr on ( ) θ ξ . Here, we analyzed that temperature field diminishes by means of escalation in Pr . Bigger estimations of Pr connects to lesser heat conductivity, hence the temperature profile is diminished. Figure 13a illustrates

Comparison of HAM with Numerical Result
We solve the system the model Equations (9)-(11) with boundary conditions (12) by ND Solve in Mathematica 10 package. Comparison between analytical and numerical techniques is shown in Tables 3 and 4. An excellent agreement is fund.

Conclusions
The squeezing Casson nanofluid flow with viscous dissipation and entropy generation between two parallel stretching plates has been presented in this paper. The stretching plates are considered porous. The impact of magnetic field is also reflected in the proposed model. The impacts of embedded parameters are shown through figures and tables.
The significant facts of the presented model are as follows: • The Casson parameter, porosity parameter, magnetic field parameter, and rotation parameter reduced the velocity profile f (ξ) while the squeezing and suction parameters increased the velocity profile f (ξ). • The Casson parameter, porosity parameter, magnetic field parameter, and rotation parameter showed dual behavior in the velocity profile f (ξ).

•
The squeezing parameter \ increased the velocity profile f (ξ) while the suction parameter reduced the velocity profile f (ξ).

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The Eckert numbers and squeezing parameter increased the temperature profile θ(ξ) while the Prandtl number increased the temperature profile θ(ξ).

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The Prandtl number, porosity parameter, and Eckert numbers increased the Entropy generation rate Ns(ξ).

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The porosity parameter increased the Bejan number Be(ξ) while the Eckert and Prandtl numbers increased the Bejan number.