An explicit and non-iterative moving-least-squares immersed-boundary method with low boundary velocity error

TL;DR

This paper introduces a non-iterative, explicit correction technique for the moving-least-squares immersed boundary method that significantly reduces boundary velocity errors with less computational effort.

Contribution

A novel uniform force correction method is proposed to improve boundary force accuracy in immersed boundary simulations, compatible with existing schemes and reducing computational cost.

Findings

Reduces residual boundary velocity to iterative method levels

Requires less computational time than iterative approaches

Effective for both stationary and moving boundaries

Abstract

In this work, based on the moving-least-squares immersed boundary method, we proposed a new technique to improve the calculation of the volume force representing the body boundary. For boundary with simple geometry, we theoretically analyse the error between the desired volume force at boundary and the actual force given by the original method. The ratio between the two forces is very close to a constant. Numerical experiments reveal that for complex geometry, this ratio exhibits very narrow distribution around certain value. A spatially uniform coefficient is then introduced to correct the force and fixed by the least-square method over all boundary markers. Such method is explicit and non-iterative, and can be easily implemented into the existing scheme. Several test cases have been simulated with stationary and moving boundaries. Our new method can reduce the residual boundary velocity to the level comparable to that given by the iterative method, but requires much less computing time. Moreover, the new method can be readily combined with the iterative method and further reduces the residual boundary velocity.