Impact of nonlinear thermal radiation on stagnation-point flow of a Carreau nanofluid past a nonlinear stretching sheet with binary chemical reaction and activation energy

This research peruses the characteristics of nanoparticles on stagnation point flow of a generalized Newtonian Carreau fluid past a nonlinear stretching sheet with nonlinear thermal radiation. The process of mass transfer is modeled using activation energy and binary chemical reaction along with the Brownian motion and thermophoresis. For energy activation a modified Arrhenius function is invoked. With regard to the solution of the governing differential equations, suitable transformation variables are used to obtain the system of nonlinear ordinary differential equations before being numerically solved using the shooting method. Graphical results are shown in order to scrutinize the behavior of pertinent parameters on velocity, temperature profiles, and concentration of nanoparticle. Also, the behavior of fluid flow is investigated through the coefficient of the skin friction, Nusselt number, Sherwood number, and streamlines. Results showed that the velocity ratio parameter serves to increase the velocity of fluid and reduces the temperature distribution and nanoparticle concentration. The results were compared with the available studies and were found to be in excellent agreement

Unsteady boundary layer flow over a sphere in a porous medium

This study focuses on the problem of unsteady boundary layer flow over a sphere in a porous medium. The governing equations which consists of a system of dimensional partial differential equations is applied with dimensionless parameter in order to obtain non-dimensional partial differential equations. Later, the similarity transformation is performed in order to attain nonsimilar governing equations. Afterwards, the governing equations are solved numerically by using the Keller-Box method in Octave programme. The effect of porosity parameter is examined on separation time, velocity profile and skin friction of the unsteady flow. The results attained are presented in the form of table and graph

Forced convective of micropolar fluid on a stretching surface of another quiescent fluid

In this paper, the problem of forced convection flow of micropolar fluid of lighter density impinging orthogonally on another heavier density of micropolar fluid on a stretching surface is investigated. The boundary layer governing equations are transformed from partial differential equations into a system of nonlinear ordinary differential equations using similarity transformation and solved numerically using dsolve function in Maple software version 2016. The velocity, microrotation and temperature ofmicropolar fluid are analyzed. It is found that both upper fluid and lower fluid display opposite behaviour when micropolar parameter K various with strong concentration n= 0, Pr = 7 and stretching parameter λ= 0.5. The results also show that stretching surface exert the force that increasing the velocity of micropolar fluid

MHD free convective flow past a vertical plate

The free convective flow in incompressible viscous fluid past a vertical plate is studied under the presence of magnetic field. The flow is considered along the vertical plate at x-axis in upward direction and y-axis is taken normal to it. The governing equations are written in vector form. Afterwards, the equations are solved numerically using finite element method with automated solution techniques. Later, the effects of magnetic field strength to the velocity and temperature of the fluid are obtained. It is found that for heated plate, the velocity and the temperature of the fluid decreases when the magnetic field strength increases. Meanwhile for cooled plate, the velocity decreases but the temperature increases when the magnetic field strength increases

Modified Seird model: a novel system dynamics approach in modelling the spread of Covid-19 in Malaysia during the pre-vaccination period

Mathematical modelling is an effective tool for understanding the complex structures and behaviors of natural phenomena, such as coronavirus disease 2019 (COVID-19), which is an infectious disease caused by a life-threatening virus called SARS-CoV-2. It has rapidly spread across the world in the last three years, including Malaysia. Adopting a novel system dynamics approach, this paper aims to explain how mathematics can play a significant role in modelling the COVID-19 spread and suggests practical methods for controlling it. It forecasts the data of infected (I), recovered (R) and death (D) cases for decision-making. This paper proposes a modified Susceptible-Exposed-Infected-Recovered-Death (SEIRD) model with time-varying parameters considering the sporadic cases, the reinfection cases, the implementation of a movement control order, and the percentage of humans abiding by the rules to forecast future growth patterns of COVID-19 in Malaysia and to study the effects of the consideration on the number of forecasted COVID-19 cases, during the pre-vaccination period. This study implemented the preliminary stage of forecasting the COVID-19 data using the proposed SEIRD model and highlighted the importance of parameter optimization. The mathematical model is solved numerically using built-in Python function ‘odeint’ from the Scipy library, which by default uses LSODA algorithm from the Fortran library Odepack that adopts the integration method of non-stiff Adams and stiff Backward Differentiation (BDF) with automatic stiffness detection and switching. This paper suggests that the effects of factors of sporadic cases, reinfection cases, government intervention of movement control order and population behavior are important to be studied through mathematical modelling as it helps in understanding the more complex behavior of COVID-19 transmission dynamics in Malaysia and further helps in decision-making

MHD forced convective flow past a vertical plate: an automated solution approach

The forced convection flow in incompressible viscous fluid past a vertical plate is investigated with the effect of magnetic field. The governing equations are solved numerically using automated solution technique which is FEniCS. It is shown that the increasing of magnetic field strength lead to decrease the velocity but increase the temperature for cooled plate. Meanwhile for heated plate, increasing magnetic field strength lead to decrease the velocity and the temperature of the fluid

Financial network (FiNe): a web application to assist investors in avoiding herding behaviour in stock market

Herding behaviour is one of the behavioural phenomena that can be observed among investors in the financial markets. Generally, investors feel more secure if they copy and follow other investors. Regardless of the market's performance, Investors are focused on their own personal and confidential information, rather than relying on publicly available market data. During market stress, herding will be more common. Investors herding together would cause market imbalances and stock prices may deviate from their fundamental values as a result of the herding phenomenon. To avoid herding behaviour among investors, a web application of financial network (FiNe) is developed to assist investors in making informed decisions quickly in order to select stocks for their portfolios based on their own analyses rather than solely relying on what other investors are doing. FiNe application displays an interactive financial network that visualizes the relationship between stocks in which the input is based on closing prices of stocks. In addition, it is also able to display financial networks for different filters such as duration and sectorial basis. With the relationships between stocks displayed in the network, investors are able to run a quick analysis and financial information on stocks for portfolio selection

Modelling transmission dynamics of covid-19 during Pre-vaccination period in Malaysia: a predictive guiseird model using streamlit

Coronavirus disease (COVID-19) is a major health threat worldwide pandemic, first identified in Malaysia on 25 January 2020. This outbreak can be represented in the mathematical expressions of a non-linear system of ordinary differential equations (ODEs). With the lack of a predictive SEIRD model in terms of Graphical Users Interface (GUI) in Malaysia, this paper aims to model the COVID-19 outbreak in Malaysia during the pre-vaccination period using the Susceptible-Exposed-Infected-Recovered-Death (SEIRD) model with time-varying parameters, then develop a GUI-SEIRD predictive model using Streamlit Python library. This GUI-SEIRD predictive model considers different values of the proportion of the quarantine-abiding population (r) and three different decisions of MCO lifted date to forecast the number of active cases (I) on 15 October 2020 that gives insightful information to government agencies. The mathematical model is solved using Scipy odeint function, which uses Livermore Solver for Ordinary Differential Equations with an Automatic method switching (LSODA) algorithm. The time-varying coefficients of SEIRD model that best fit the real data of COVID-19 cases are obtained using the Nelder-Mead optimization algorithm. This an extended SIRD model with exposed (E) compartment becoming SEIRD, leads to a robust model. It adequately fitted two datasets of Malaysian COVID-19 indicated by the slightest average values of root mean square error (RMSE) as compared to other existing models. The results highlight that the larger the values of the proportion of the quarantine-abiding population (r) and the later the date of the lifted MCO, the faster Malaysia reaches disease free equilibrium

Effects of Heat Generation/Absorption on a Stagnation Point Flow Past a Stretching Sheet Carbon Nanotube Water-Based Hybrid Nanofluid with Newtonian Heating

This study investigates the mathematical modelling of heat generation/absorption effect on the convective flow of single wall carbon nanotube-copper (SWCNT-Cu)/water hybrid nanofluid towards a stagnation point past a stretching sheet with Newtonian heating. The set of governing equations in the form of non-linear partial differential equations are first transform using the similarity transformation technique then solved numerically by the Runge-Kutta-Fehlberg (RKF45) method in Maple software. The numerical solutions were obtained for the surface temperature, the heat transfer coefficient and the skin friction coefficient as well as the velocity and the temperature profiles. The features of the flow and heat transfer characteristics for various values of the stretching parameter, the conjugate parameter, the nanoparticle volume fraction parameter and the heat source/sink parameter are analyzed and discussed. It is found that effects of hybrid nanoparticles are more significant for lower stretching parameter and for large conjugate parameter values, as well as the heat generation/absorption