A solution of the governing equation representing drawdown in a horizontal confined aquifer, where groundwater flow is unsteady, was first provided by Theis and famously known as solution. This given terms an exponential integral, also called well function, for which simple reliable approximations are preferred due to their practical applications. To that end, several available literature, some...

Multispecies pollutant migration often occurs in polluted groundwater systems. Most of the multispecies problems that have been dealt literature assume constant transport parameters, primarily because analytical solutions for varying parameters become a challenge. The present study analytically solves two-species convection-dispersion equation, considering spatially dispersion coefficient and s...

in this paper, elzaki homotopy perturbation method is employed for solving linear and nonlinear differential equations with a variable coffecient. this method is a combination of elzaki transform and homotopy perturbation method. the aim of using elzaki transform is to overcome the deficiencies that mainly caused by unsatised conditions in some semi-analytical methods such as homotopy perturbat...

In this manuscript, a semianalytical solution of the time-fractional Navier-Stokes equation under Caputo fractional derivatives using Optimal Homotopy Asymptotic Method (OHAM) is proposed. The above-mentioned technique produces an accurate approximation desired solutions and hence known as approach. main advantage OHAM that it does not require any small perturbations, linearization, or discreti...

This paper presents a new method for solving a class of infinite horizon nonlinear optimal control problems. In this method, first the original optimal control problem is transformed into a nonlinear two-point boundary value problem (TPBVP) via the Pontryagin’s maximum principle. Then, using the homotopy perturbation method and introducing a convex homotopy in topologic space, the nonlinear TPB...

although homotopy-based methods, namely homotopy analysis method andhomotopy perturbation method, have largely been used to solve functionalequations, there are still serious questions on the convergence issue of thesemethods. some authors have tried to prove convergence of these methods, butthe researchers in this article indicate that some of those discussions are faulty.here, after criticizi...

in this study, a new efficient semi-analytical method is introduced to give approximate solutions of strongly nonlinear oscillators. the proposed method is based on combination of two different methods, the multi-step homotopy analysis method and spectral method, called the multi-step spectral homotopy analysis method (msham). in this method, firstly, we propose a new spectral homotopy analysis...