Wake phase interference for passive self-damping of pressure fluctuations in a negative curvature valve

Passive control of pressure fluctuations in internal flows is of fundamental interest in stability-sensitive hydraulic and transport systems. This study develops a phase-based concept for understanding passive filtering effects arising from wake-forcing interaction. Specifically, the analysis demonstrates that downstream pressure modulation is governed by amplitude-phase coupling within the wake, rather than by vortex intensity alone. On this basis, a theoretical criterion is derived to distinguish regimes of attenuation and amplification, thereby identifying vortex strength, phase separation, and modal coherence as the key controlling parameters. To validate the proposed criterion, a spherical check valve and several concave modifications are examined as a representative configuration. The finite-element simulations show that attenuation can be achieved either by strengthening a dominant vortex or by increasing vortex multiplicity. Under an optimal concave geometry, the peak pressure fluctuation amplitude is reduced by up to 58.4% relative to the spherical valve. Conversely, excessive vortex fragmentation degrades coherence and shifts the system into amplification. Furthermore, tests under triangular forcing and varying amplitudes reveal that the mechanism persists under broader spectral conditions, although its efficiency is ultimately governed by timescale competition between vortex formation and external forcing.