http://hdl.handle.net/123456789/14520 Sat, 04 Apr 2026 12:26:17 GMT 2026-04-04T12:26:17Z http://hdl.handle.net/123456789/19053 Non-Orthogonal Stagnation Point Flow of a Nanofluid along a Moving Surface Tabinda Sajjad, 01-283191-001 Non- orthogonal stagnation point flow is the generalization of Hiemanz flow. This flow contains an orthogonal stagnation-point flow to which is added a shear flow whose vorticity is fixed at infinity. Non-orthogonal stagnation point flow was first ever discussed by Stuart. It is observed that the streamlines near a stagnation point are tilted outward due to normal stress working in the stagnation point flow. Non-orthogonal stagnation point flows appeared in many physical phenomena, in industry, instrumentation, engineering, and anterior cerebral flows in humans. In the present thesis, we have to deal with the models related to non-orthogonal flows along the vertical and horizontal stretching surfaces. When it comes to nanofluids, non-orthogonal flows with nanoparticles can achieve exciting thermal conduction properties. Non-orthogonal stagnation point flows of Newtonian and non-Newtonian nanofluids are the main focus of this dissertation. This study comprises mathematical models, numerical solutions, graphical and tabular results for mass and heat transfer characteristics, and flow patterns of a nanofluid along vertical and horizontal stretching surfaces. The thermal aspects of nanoparticles are incorporated into the mathematical models by using various thermal conductivity models for nanofluids. The modified Chebyshev collocation method is used for the analysis. It is a recently developed numerical method using the Picard iterative technique and it can tackle nonlinear systems of differential equations with an accuracy of 10−7. The novelty of this study comprises mainly the application of the modified Chebyshev collocation method for solutions of highly nonlinear coupled differential equations, the mixed convection analysis, and thermal aspects of nanofluids with various effects including double diffusion, entropy generation, porous medium, and magnetic field. It is found that in the non-orthogonal flows the temperature gradient is reduced by enhancing the stretching parameter and the angle of the strike. The skin friction on the stretching surfaces is also affected by the angle of incidence. Supervised by Dr. Rizwan Ul Haq Mon, 01 Jan 2024 00:00:00 GMT http://hdl.handle.net/123456789/19053 2024-01-01T00:00:00Z http://hdl.handle.net/123456789/20509 Similar and Non-Similar Solutions of Hybrid Nanofluid Flows Over Different Geometries Nazia Shahmir, 01-283202-001 This thesis discusses the similar and non-similar solutions of the hybrid nanofluid flows over varied geometries. Hybrid nanofluids are more versatile than traditional fluids because they have better heat transfer properties. This makes them highly appropriate for a wide range of applications, such as solar energy systems, power generation, and cooling/heating processes. The geometries discussed in this thesis are wedge, exponential, inclined, and horizontal stretching surfaces. In addition, the dynamics of the hybrid nanoliquid due to a static horizontal sheet are also deliberated. Many theoretical fluid models seek solutions through self-similar and similar solutions. However, these solutions may contain parameters with variable terms. This thesis introduces non-similar solutions, which eliminates the possibility of encountering parameters with variable terms. The unique models presented in this thesis include numerous effects including Newtonian heating (local surface temperature determines how much heat is transferred from the surface), viscous heating (heat produced by the friction of two adjacent layers of fluid), and Joule heating (electrical resistance heating), surface catalyzed reactions (reactions in porous media with homogeneous/heterogeneous reactions), quadratic convection (quadratic density variation with temperature), and Cattaneo-Christov heat flux (finite heat propagation time), etc. The outcomes are delineated through the use of charts and tables. Apart from the literature review, the introduction to the basic terms in the thesis, the future work, the thesis contains a non-similar solution of the comparison of ternary and hybrid nanoliquid flows over a wedge considering the impacts of the quadratic thermal convection and frictional and Newtonian heating in a permeable medium. The work is also supported by the surface-catalyzed in homogeneousheterogeneous (H-H) reactions duo. This is followed by another delicate model presenting a heat transfer comparison of ferromagnetic hybrid nanoliquid flows along an exponentially stretched geometry in a permeable medium influenced by an induced magnetic flux. The consequences of the surface catalyzed in the utilization of the H-H reactions with entropy generation analysis is also considered. Here, a non-similar solution is obtained up to second-order truncation. The third model also deliberates the non-similar solution up to the second-order truncation of a unique model discussing the hybrid nanoliquid flow including carbon nanotubes of both types immersed into the base water over an inclined stretched surface. The analysis is conducted considering the consequences of the quadratic convection amalgamated with viscous dissipation, and non-linear radiative flux with the effects of velocity and thermal slips. Modified Hamilton-Crosser and Xue’s models are considered for the heat transfer analysis. The mechanism of irreversibility is also calculated. The resulting solution of this model is also non-similar. The second last problem examines a comparison of Brinkman, Timofeeva, and Yamada Ota for the particles’ shape thermal efficiency in (C2H6O2)-based hybrid nanoliquid flow through a static geometry with a free stream velocity. The said model also considers the ramifications of the linear radiative heat flux, heat generation, viscous and ohmic dissipations with convective boundary conditions. The last model in the thesis discusses the comparative assessment of heat transmission of mono and hybrid nanoliquid flows along a bidirectional extending surface with prescribed surface temperatures amalgamated with Cattaneo-Christov thermal flux in the incidence of magnetic flux. A similar solution to the computed problem is discussed. The authentication of the outcomes is also embedded in each presented chapter portraying the truthfulness of the specific model. All the numerical results are obtained numerically via bvp4c scheme. The significance of this thesis lies in finding similar and non-similar solutions to the presented unique models. Supervised by Dr. Muhammad Ramzan Mon, 01 Jan 2024 00:00:00 GMT http://hdl.handle.net/123456789/20509 2024-01-01T00:00:00Z http://hdl.handle.net/123456789/17065 Convection Analysis in Closed Cavity Via Fem Approach Syed Saqib Shah, 01-283181-003 Thermal management in closed cavity is one of the most important analysis in recent decade. Such type of heat analysis in the presence of molecular movement is convection. The simulation of Heat and mass transfer through various type of convection in complex geometries is studied in this dissertation. The analysis of FEM on heat transportation in a two dimensional closed cavity is much challenging and depending upon the complex nature of the problem. However, to ensure the e - cient and accurate analysis, the following considerations of signi cant criteria may be taken as; Mesh density, Element type, Boundary Conditions, Material Properties of structure, the solution and its method and the criteria to check its convergence. Aim of this work is to develop various geometries (square, trapezoidal, circular, curved and corrugated) for engineering and industries as cooling equipment, thermal energy storage, thermal solar equipments etc. through ns, obstacles and lid walls. Mathematical non-linear Partial Di erential Equations (PDEs) and boundary conditions are developed. For such physical two dimensional problems, steady-state equations of continuity, momentum, energy and concentration are developed, which are nondimensionalized by using suitable dimensionless variables. For solution of strong non-linear PDEs in dimensionless form in this thesis, computational method as Finite Element Method (FEM) is adopted. For numerical approach, Glarekin residual approach of FEM is applied in which rst domain is discretized into sub-domain in the form of quadrilateral and triangular form etc. Each sub-domain formulation occurs with combination of nodes, which form elements. Acquired elements are solved in the form of simultaneous algebraic equations for unknown interior nodes, these elements of sub-domain develop sti ness matrix for numerical simulation. Union of elements form domain of the cavity or enclosure. Simulation of structure for natural, forced and mixed convection are taken in this thesis. Impact of various rising parameters on streamlines, isotherms, iso-concentration, velocity, tempera ture, local and average Nusselt number are presented in the form of graphs. The emphasis on heat transfer in cavity due to forced, natural and mixed convection are obtained. Numerical and graphical interpretation of problems are discussed in comparison with experimental and numerical results. Mesh analysis and grid independence test for various cavity are analysed for average Nusselt number. Number of nodes or response of meshes on rate of heat transfer are calculated. Validation of the current work with literature in limited cases are explored. In case of square cavity, size of heated n increases the heat transfer inside cavity. Convection process shows signi cant transfer rate of heat at mean position with increase in nanoparticles in enclosure. Heat driven through lid walls in case of forced convection in porous corrugated duct in the presence of heat generation. Partially lid driven of top lid walls move inside direction generate more heat in enclosure. In concentration of nano uids, Lewis number and buoyancy increase mass transfer and Re increases heat transfer inside enclosure. Forced convection in circular duct through triangular ns is signi cantly a ected with Re, Da and . Reynolds number increases heat in cavity while porosity and nanoparticle decrease heat in cavity with increasing the parameter. Q > 0 plays a vital role for heat generation inside cavity in all problems. Supervised by Dr. Rizwan Ul Haq Sun, 01 Jan 2023 00:00:00 GMT http://hdl.handle.net/123456789/17065 2023-01-01T00:00:00Z http://hdl.handle.net/123456789/14525 Impact of Cattaneo-Christov Heat Flux in Newtonian and Non-Newtonian Nanofluid Flows Hina Gul, 01-283182-001 Analysis of heat and mass transfer of Newtonian and non-Newtonian nanofluid flows in varied complex geometries emphasizing Cattaneo-Christov heat flux is elucidated in this thesis. This thesis focuses on the problems that concentrate on the modified Fourier law which is the upgraded form of the classical Fourier law under various scenarios and geometries including disk, cylinder, and sheets extended in two and three dimensions. The topic of fluid flows due to nanofluid has also been the epicenter of discussion owing to its widespread industrial and mechanical applications in biomedical such as cancer therapy. Measuring heat transfer can be useful in assessing the amount of heat transported through a wall or a nervous system, or the quantity of gamma-ray or solar radiant energy delivered to a specific area. Using a heat flux detector under natural convection conditions could be effective for lower-powered devices. Nanofluid is used to cool microchips in computers, radiators in automobiles, and energy storage systems. The envisioned flow models encompass the effects of variable thermal conductivity and diffusion coefficients, heat generation/absorption, non-uniform heat source-sink, viscous dissipation, velocity, and thermal slips, convective boundary conditions, homogenous-heterogenous reactions with surface catalyzed reaction, and gyrotactic microorganism in different geometries. The renowned hybrid nanofluid models namely Yamada-Ota, Hamilton-Crosser, and Xue following Tawari and Das flow pattern are considered. The geometries considered in this thesis include two and three-dimensional flows, flow over a rotating disk, a cylinder, and in a channel. The physical flow model, which takes the form of differential equations, is governed by boundary layer approximations. For various values of the emergent parameters, physical quantities like velocities, temperature, concentration, Sherwood and Nusselt numbers, and skin friction coefficients are computed numerically and examined in depth. A MATLAB built-in function bvp4c is used to draw the association of varied profiles with parameters through graphical illustrations and to validate the findings by comparing them with earlier published works. An excellent correlation between the results is obtained. The key finding of this thesis leads to conclude that the results of hybrid nanofluid are dominant as compared to nanofluid flow and similarly Yamada-Ota model achieves better results than the Xue model. The velocity and temperature of dust particles increase as the fluid-particle interaction parameter increases. The greater thermal relaxation time parameter decreases the fluid temperature. The significance of our study is the that heat transfer phenomenon is applicable in various physical situations and manufacturing processes are designed to maximize efficiency. Supervised by Dr. Muhammad Ramzan Sat, 01 Jan 2022 00:00:00 GMT http://hdl.handle.net/123456789/14525 2022-01-01T00:00:00Z