Murad Ullah

Interval-valued Pythagorean fuzzy geometric aggregation operators and their application to group decision making problem

There are many aggregation operators have been defined up to date, but in this work, we define the interval valued Pythagorean fuzzy weighted geometric (IPFWG) operator, the interval-valued Pythagorean fuzzy ordered weighted geometric (IPFOWG) operator, and the interval-valued Pythagorean fuzzy hybrid geometric operator. We also discuss some properties and give some examples also to develop these operators. At the last we apply the interval-valued IPFWG operator and the interval-valued IPFOWG operator to multiple attribute decision-making problem under the interval-valued Pythagorean fuzzy information.

Double-layer optical fiber coating analysis using viscoelastic Sisko fluid as a coating material in a pressure-type coating die

Abstract. Double-layer optical fiber coating is performed using a melt polymer satisfying a Sisko fluid model in a pressure-type die. For this purpose, wet-on-wet coating process is applied. The assumption of fully developed flow of a Sisko fluid model, two-layer liquid flows of an immiscible fluid is modeled in an annular die of length L, where the bare glass fiber is dragged at a higher speed. The nonlinear governing equations are modeled and then solved by utilizing optimal homotopy asymptotic method (OHAM). The convergence of series solution is established. The convergence of OHAM is also verified by the Adomian decomposition method. In addition, the shear-thinning and shear-thickening characteristics of the non-Newtonian Sisko fluid are examined, and a comparison is made with the Newtonian fluid. At the end, the present work is also compared with the experimental results already available in the literature by taking the non-Newtonian parameter that tends to zero.

Solution of magnetohydrodynamic flow and heat transfer of radiative viscoelastic fluid with temperature dependent viscosity in wire coating analysis

Wire coating process is a continuous extrusion process for primary insulation of conducting wires with molten polymers for mechanical strength and protection in aggressive environments. In the present study, radiative melt polymer satisfying third grade fluid model is used for wire coating process. The effect of magnetic parameter, thermal radiation parameter and temperature dependent viscosity on wire coating analysis has been investigated. Reynolds model and Vogel’s models have been incorporated for variable viscosity. The governing equations characterizing the flow and heat transfer phenomena are solved analytically by utilizing homotopy analysis method (HAM). The computed results are also verified by ND-Solve method (Numerical technique) and Adomian Decomposition Method (ADM). The effect of pertinent parameters is shown graphically. In addition, the instability of the flow in the flows of the wall of the extrusion die is well marked in the case of the Vogel model as pointed by Nhan-Phan-Thien.

Analytical and numerical solutions of Oldroyd 8-constant fluid in double-layer optical fiber coating

Polymer flow during wire coating in a pressure-type casting die has been simulated under non-isothermal conditions. The flow is dependent on the wire velocity, geometry of the die, and the viscosity of the polymer. In the present study, the constitutive equation of an Oldroyd 8-constant fluid is used to characterize the rheology of the polymer melt. The equation describing the flow of polymer melt inside the die is solved (1) analytically by applying optimal homotopy asymptotic method (OHAM) and (2) numerically by the shooting method with Runge–Kutta–Fehlberg algorithm. The convergence of the series solution is established. The effect of physical characteristics of the problem has been discussed in detail through graphs by assigning numerical values for several parameters of interest. At the end, the present study is also compared with published work as a particular case and good agreement is found.