Feeling the Flow: A Real‐Time Multimodal Visuo‐Haptic Interface for Interactive Fluid Dynamics in XR

In Extended Reality (XR), fluid dynamics are predominantly conveyed through visual cues alone. The absence of tangible feedback limits immersion and the perception of intrinsic physical properties such as viscosity and flow regime transitions. We present “Feeling the Flow”, a real‐time multimodal interface integrating GPU‐accelerated Lattice Boltzmann Method (LBM) simulation with high‐fidelity haptic feedback. To address the frequency mismatch between visual and haptic channels, we introduce a multi‐rate asynchronous architecture that enables 1000 Hz physics updates on consumer hardware. A key contribution is our Reynolds‐number‐based dynamic spectral modulation mechanism: unlike conventional linear force amplification, this method modulates the haptic signal's spectral content according to flow regime, producing smooth forces in laminar flow and progressively introducing multi‐scale turbulent textures as Reynolds number increases. Technical validation demonstrates real‐time performance, high numerical accuracy, and correct capture of vortex‐shedding dynamics. A controlled user study () demonstrates that the multimodal interface significantly enhances perception of complex flow dynamics by 47.1% () without increasing cognitive load, highlighting the potential of physics‐aware haptics in immersive XR experiences.