A non-singular fractional-order logistic growth model with multi-scaling effects to analyze and forecast population growth in Bangladesh.

This paper is primarily concerned with data analysis employing the nonlinear least squares curve fitting method and the mathematical prediction of future population growth in Bangladesh. Available actual and adjusted census data (1974-2022) of the Bangladesh population were applied in the well-known autonomous logistic population growth model and found that all data sets of the logistic (exact), Atangana-Baleanu-Caputo (ABC) fractional-order derivative approach, and logistic multi-scaling approximation fit with good agreement. Again, the existence and uniqueness of the solution for fractional-order and Hyers-Ulam stability have been studied. Generally, the growth rate and maximum environmental support of the population of any country slowly fluctuate with time. Including an approximate closed-form solution in this analysis confers several advantages in assessing population models for single species. Prior studies predominantly employed constant growth rates and carrying capacity, neglecting the investigation of fractional-order methods. Thus, the current study fills a crucial gap in the literature by introducing a more formal approach to analyzing population dynamics. Therefore, we bank on the findings of this article to contribute to accurate population forecasting and planning, national development, and national progress.

Finite element analysis of double-diffusive natural convection in a porous triangular enclosure filled with Al2O3 -water nanofluid in presence of heat generation.

The problem of double-diffusive natural convection of Al2O3 -water nanofluid in a porous triangular enclosure in presence of heat generation has been studied numerically in this paper. The bottom wall of the cavity is heated isothermally, the left inclined wall is non-isothermal and the right inclined wall is considered to be cold. The concentration is higher at bottom wall, lower at right inclined wall and non-isoconcentration at left inclined wall of the cavity. The governing equations are transformed to the dimensionless form and solved numerically using Galerkin weighted residual technique of finite element method. The results are obtained in terms of streamlines, isotherms, isoconcentrations, average Nueeslt number (Nu) and average Sherwood number (Sh) for the parameters thermal Rayleigh number (RaT ), dimensionless heat generation parameter (λ), solid volume fraction (ϕ) and Lewis number (Le) while Prandtl number (Pr), Buoyancy ratio (N) and Darcy number (Da) are considered to be fixed. It is observed that flow pattern, temperature fields and concentration fields are affected by the variation of above considered parameters.