[Светлана]

I would like to obtain the value of shear stress acting on the particles from the tangential velocity component (10.1002/ceat.201500378 Equation 1). Evaluating this variable requires the knowledge of spatial derivatives such as the derivative of the tangential particle velocity (where the particles are revolving around an axis) by the radial distance of the particle location.

As far as I know Fluent provides particle history data which contain the particle coordinates (X Y Z) and the particle velocity components (U V W). If this data could be exported to MATLAB I would be able to write the derivative code myself however I only found an option to export the data to geometry or ensign or fieldview format, of which CFD-Post reads in one of these formats and provides particle track - but this does not work well as the particle track variables are then not listed in the list of variables for defining a custom expression or variable.

Please suggest what is the best way to approach this problem.