Method use UDF to strip the interest surface(where force is applied) Steps - open case file, check the *ID* of solid sourface ( cylinder/blade surface) - check the spanwise direction(such as z direction), and force direction( such lift, y axis, drag, x axis) - Make the appropriate changes in the UDF +(Axis direction, Force direction, no. of strips and ID of the wall zone) - lauch Fluent from command line + Open the Start screen (press Windows button on your keyboard, Type 'VS2013 x86 x64 Cross Tools Command Prompt' + Navigate to your working folder, i.e. the folder where your case and data files are (.cas & .dat). + Type “fluent” in the command window to launch Fluent or “C:\Program Files\ANSYS Inc\v161\fluent\ntbin\win64\fluent.exe” (quotation signs included, in case of standard installation; fluent version: 16.1). + Make sure that on the *Environment tab* 'Setup Compilation Environment for UDF' is ticked. The default address is fine. - *Co