Large core sizes are often used in hollow-core negative curvature fibers to obtain a small leakage loss. However, fibers with a large core diameter have higher-order core modes. It is desirable for many applications to suppress the higher-order modes, which decreases the coupling between the fundamental and higher-order core modes due to small perturbations like microbending. The challenge is to suppress higher-order core modes while preserving low leakage loss for the fundamental core mode. This simulation describes higher-order mode suppression in negative curvature fibers using resonant coupling between the higher-order core modes and the tube modes, while coupling of the fundamental mode to the tube modes remains inhibited.