Uncertainty Quantification in Resolvent Analysis of Experimental Wall-Bounded Turbulent Flows

TL;DR

This paper investigates how uncertainties in experimental mean flow measurements affect resolvent analysis of wall-bounded turbulence, proposing a method to quantify this sensitivity with minimal computational cost.

Contribution

It introduces a framework to assess the impact of experimental uncertainties on resolvent analysis, enhancing its reliability for turbulent flow predictions.

Findings

Sensitivity of resolvent analysis to measurement uncertainties can be quantified efficiently.

Poor near-wall resolution can lead to incorrect interpretations of turbulent flow structures.

The method is applicable to both local and biglobal resolvent analyses.

Abstract

Experimental mean flows are commonly used to study wall-bounded turbulence. However, these measurements are often unable to resolve the near-wall region and thus introduce ambiguity in the velocity closest to the wall. This poses a source of uncertainty in equation-based approaches that rely on these mean flow measurements such as resolvent analysis. Resolvent analysis provides a scale-dependent decomposition of the linearized Navier Stokes equations that identifies optimal gains, response modes and forcing modes that has been used to great effect in turbulent wall-bounded flows. Its potential in the development of predictive tools for a variety of wall-bounded flows is high but the limitations of the input data must be addressed. Here, we quantify the sensitivity of resolvent analysis to common sources of experimental uncertainty and show that this sensitivity can be quantified with minimal additional computational cost. This approach is applied to both local and biglobal resolvent analysis by using artificial disturbances to mean profiles in the former and particle image velocimetry measurements with differing near-wall fits in the latter. We also highlight an example where poor near-wall resolution can lead to erroneous conclusions compared to the full-resolution data in an adverse pressure gradient turbulent boundary layer.