Assessment of complex variable basis functions in the approximation of ideal fluid flow problems

Solving potential problems, such as those that occur in the analysis of steady-state heat transfer, electrostatics, ideal fluid flow, and groundwater flow, is important in several fields of engineering, science, and applied mathematics. Numerical solution of the relevant governing equations typically involves using techniques such as domain methods (including finite element, finite difference, or finite volume), or boundary element methods (using either real or complex variables). In this paper, the Complex Variable Boundary Element method (“CVBEM”) is examined with respect to the use of different types of basis functions in the CVBEM approximation function. Four basis function families are assessed in their solution success in modeling an important benchmark problem in ideal fluid flow; namely, flow around a 90 degree bend. Identical problem domains are used in the examination, and identical degrees of freedom are used in the CVBEM approximation functions. Further, a new computational modeling error is defined and used to compare the results herein; specifically, M = E / N where M is the proposed computational error measure, E is the maximum difference (in absolute value) between approximation and boundary condition value, and N is the number of degrees of freedom used in the approximation.