Numerical solution of space-time variable fractional order advection-dispersion equation using radial basis functions

This paper aims to advance the radial basis function method for solving space-time variable-order fractional partial differential equations. the fractional derivatives for time and space are considered in the coimbra and the riemann-liouville sense, respectively. first, the time-variable fractional derivative is discretized through a finite difference approach. then, the space-variable fractional derivative is approximated by radial basis functions. also, we advance the rippa algorithm to obtain a good value for the shape parameter of the radial basis functions. results obtained from numerical experiments have been compared to the analytical solutions, which indicate high accuracy and efficiency for the proposed scheme.