# Validation of Taylor’s Frozen Hypothesis for DAS-Based Flow

## TL;DR

This study validates Taylor’s frozen hypothesis for non-intrusive flow measurement using DAS in turbulent circular pipes, showing high accuracy and stability.

## Contribution

The paper introduces a novel dispersion feature enhancement algorithm and experimentally validates Taylor’s hypothesis with DAS for circular pipe flow.

## Key findings

- Turbulent flow vortex structures in circular pipes remain stable in the convection direction, supporting Taylor’s hypothesis.
- The proposed method achieves ≤3% relative error in average flow velocity with improved accuracy in high-flow zones.
- A DAS-based system was successfully used for signal denoising and flow velocity verification in turbulent conditions.

## Abstract

Accurate measurement of pipeline flow is of great significance for industrial and environmental monitoring. Traditional intrusive methods have the disadvantages of high cost and damage to pipeline structure, while non-intrusive techniques can circumvent such issues. Although Taylor’s frozen hypothesis has a theoretical advantage in non-intrusive velocity detection, current research focuses on planar flow fields, and its applicability in turbulent circular pipes remains controversial. Moreover, there is no precedent for combining it with distributed acoustic sensing (DAS) technology. This paper constructs a circular pipe turbulence model through large eddy simulation (LES), revealing the spatiotemporal distribution characteristics of turbulent kinetic energy and the energy propagation rules of FK spectra. It proposes a dispersion feature enhancement algorithm based on cross-correlation, which combines a rotatable elliptical template with normalized cross-correlation coefficients to suppress interference from non-target directions. An experimental circulating pipeline DAS measurement system was set up to complete signal denoising and compare two principles of flow velocity verification. The results show that the vortex structure of turbulent flow in circular pipes remains stable in the convection direction, conforming to theoretical premises; the relative error of average flow velocity by this method is ≤3%, with significant improvements in accuracy and stability in high-flow zones. This study provides innovative methods and experimental basis for non-intrusive flow detection using DAS.