A cubic autocatalator chemical reaction model with limit cycle analysis and consistency preserving discretization

This article deals with the study of some qualitative properties of a cubic autocatalator chemical reaction model. Particularly, we obtain a dynamically consistent cubic autocatalator discrete-time model by applying a nonstandard difference scheme. Analysis of the existence of equilibria and their stability is carried out. It is proved that a continuous system undergoes the Hopf bifurcation at its interior equilibrium, whereas the discrete-time version undergoes Neimark-Sacker bifurcation at its interior fixed point. Moreover, numerical simulation is provided to strengthen our theoretical discussion.

Bifurcation analysis of a discrete-time four-dimensional cubic autocatalator chemical reaction model with coupling through uncatalysed reactant

In this manuscript, we discuss a four-dimensional cubic autocatalator chemical reaction model in continuous form. We investigate the existence of one and only positive fixed point and then we have obtained some parametric conditions for local stability of continuous system by using Routh-Hurwitz stability criteria. Moreover, we discretize the four-dimensional continuous cubic autocatalator chemical reaction model by using Euler’s forward method and then by using a nonstandard difference scheme we obtained a consistent discrete-time counterpart of four-dimensional cubic autocatalator chemical reaction model. Parametric conditions for local asymptotic stability of one and only positive fixed point of obtained system are also discussed. It is shown that the obtained system experiences the Neimark-Sacker bifurcation at one and only positive fixed point by using a general standard for Neimark-Sacker bifurcation. The discrete-time counterpart of genuine four-dimensional system displays chaotic dynamics at different standards of bifurcation parameter. Furthermore, the control of Neimark-Sacker bifurcation and chaos is also deliberated by using a generalized hybrid control scheme, which is based on parameter perturbation and feedback control. Finally, some numerical examples are given to strengthen our theoretical results.

Bödewadt Flow Over a Permeable Disk with Homogeneous-Heterogeneous Reactions: A Numerical Study

We analyzed the onset of homogeneous-heterogeneous reactions in Bödewadt flow occurring over an isothermal and permeable surface. This research is based on the assumption that the homogeneous (bulk) reaction follows isothermal cubic autocatalator kinetics, whereas the surface reaction is governed by first-order kinetics. The heat energy released during the chemical reaction is assumed to be negligible. The governing equations are reducible to a set of self-similar equations, which are handled numerically. Asymptotic analysis was conducted, which revealed that the existence of a concentration boundary layer on the disk is possible only when the disk is subjected to a sufficient amount of suction. In a large suction situation, an exact formula for concentration profile ϕ was derived that strongly supports the obtained numerical solution. Our results demonstrate the mass transfer parameter considerably alters flow fields. The concentration at the wall varies substantially when the chemical reaction proceeds at a faster rate.

Heat and Mass Transfer Analysis in the Stagnation Region of Maxwell Fluid With Chemical Reaction Over a Stretched Surface

A simple model of homogeneous–heterogeneous process for Maxwell fluid flow in stagnation region past a stretched surface is constructed. It is assumed that the homogeneous process in the ambient fluid is governing by first-order kinetics and the heterogeneous process on the wall surface is given by isothermal cubic autocatalator kinetics. Flow by stretched surface with homogeneous–heterogeneous processes studied. Present problem is reduced to ordinary differential equations through appropriate transformation. Resulting problems have been solved for convergent solutions. Intervals of convergence for the obtained series solutions are explicitly determined. Behavior of important variables on the physical quantities is analyzed. Velocity is found decreasing function of Deborah number.

Homogeneous–Heterogeneous Reactions in Boundary-Layer Flow of a Nanofluid Near the Forward Stagnation Point of a Cylinder

A mathematical model describing the homogeneous–heterogeneous reactions in the vicinity of the forward stagnation point of a cylinder immerged in a nanofluid is established. We assume that the homogeneous reaction is given by isothermal cubic autocatalator kinetics, while the heterogeneous reaction is chosen as first-order kinetics. The existence of multiple solutions through hysteresis bifurcations is discussed in detail for the various diffusion coefficients of reactant and autocatalyst.