Fidelity of wall tap pressure measurements in steady and pulsatile flow

Accurate wall pressure measurements quantify pressure gradients in internal flows, yet a flush wall tap is not passive: tap geometry can bias static pressure, and the tap, pressure tubing, and sensor pathway can attenuate pulsatile fluctuations. We quantify wall pressure measurement fidelity over Reynolds numbers up to 704 by separating steady tap effects, dynamic transmission, and sensitivity to as-built geometry in experiments and computational fluid dynamics (CFD). Steady tests evaluated tap diameter bias (0.4, 0.8, and 1.0 mm) and compared CFD on computer-aided design and micro-computed tomography reconstructed lumens. A symmetric phantom with mirrored taps was tested at 1 Hz to quantify attenuation for 0.5 and 1.0 mm taps and two tubing lengths (560 and 2240 mm). The workflow was applied to a patient-specific intracranial aneurysm (IA) phantom with ten taps, fabricated by three-dimensional printing. Steady cases and a sinusoidal case were compared with matched rigid-wall CFD driven by the measured inflow waveform. Tap diameter weakly affected steady differential pressure, but 0.5 mm taps attenuated pulsatile amplitude, while tubing length changed amplitude by <1% at 1 Hz. In the IA phantom, the main discrepancies were in pressure magnitude rather than spatial pattern: CFD captured normalized spatial pressure distributions but underpredicted gauge pressure by 22%–28% in steady flow, pulsatile amplitude by 42%, and peak differential pressure by 15%. These results show that agreement in waveform shape or spatial trends can coexist with large magnitude error unless pressure transmission, as-built geometry, and inlet definition are verified and uncertainties are considered.