Tuft Visualization and PINN Shear Stress Mapping for Aerodynamic Surfaces

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Solution Overview

Problem

Current methods for measuring shear stress on aerodynamic surfaces are costly, time-consuming, and suffer from reduced spatial resolution due to physical limitations and intrusive techniques, lacking efficient and accurate systems for improved design.

Innovation Solution

Combining tuft visualization with physics-informed neural networks to estimate shear stress, utilizing tufts on aerodynamic models in wind tunnels, and integrating pressure taps for data enhancement, with automatic differentiation to improve output variables.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Pressure Sensitive Paint (PSP) is used to measure surface pressure, then measurement precision is improved, but device complexity and cost increase due to extensive calibration requirements and optical access needs

Engineering Contradiction:
Improvesurface pressure measurement accuracyVSAvoidcalibration and optical access requirements
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the measurement function from complex calibrated systems (PSP) and implements it through simple tuft visualization. The tufts directly indicate flow direction and boundary layer behavior without requiring external calibration systems, optical access, or complex processing equipment.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses inexpensive tufts as disposable measurement elements that can be easily applied and removed. These tufts provide measurement information through their visual orientation and movement, eliminating the need for expensive, complex, and difficult-to-calibrate PSP systems while maintaining measurement capability.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Measurement precision

If pressure taps are installed to measure surface pressure, then measurement precision is improved, but spatial resolution is reduced due to physical access limitations and reduced number of taps

Engineering Contradiction:
Improvesurface pressure measurement accuracyVSAvoidspatial resolution
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical pressure tap system with a visual field-based measurement system using tufts. Instead of installing discrete mechanical sensors that require physical access and wiring, the tuft system uses the flow field itself to provide spatially distributed measurement information across the entire surface.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If traditional diagnostic tools are used to measure flow field, then measurement precision is improved, but loss of time increases due to costly and time-consuming procedures

Engineering Contradiction:
Improveflow field measurement accuracyVSAvoidtesting duration
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements a self-service measurement system where tufts automatically indicate flow conditions through their natural alignment and movement in the flow field. The system requires no active calibration, no complex data processing, and provides immediate visual feedback, eliminating the time-consuming procedures associated with traditional diagnostic tools.

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Provides high spatial resolution and accurate estimation of shear stress on aerodynamic surfaces, enhancing aerodynamic design efficiency and reducing costs by leveraging deep learning algorithms.

Implementation Method 1

Applying a generally horizontal dynamic flow force to the model thereby creating movement of the plurality of tufts

Methodology Applied
Scientific EffectDynamic flow force: Fluid Spray

Implementation Method 2

Utilizing the output flow variables as well as a set of pressure outputs of the model to estimate the shear walls stress of the model

Methodology Applied
Scientific EffectShear stress: Shear Stress

Data Source

PatentUS12510449B2Quantification of shear stress field using tuft visualization and deep learning
Publication Date: 2025.12.30 CALIFORNIA INST OF TECH
  • US12510449B2 patent drawing
  • US12510449B2 patent drawing
  • US12510449B2 patent drawing

AI summary

A system and method for estimating the shear wall stress of an aerodynamic surface using a tuft visualization technique combined with a physics-informed neural network. The tuft visualization technique is a simplified method of generating velocity profile data of an aerodynamic model that can subsequently be used to generate a shear wall stress profile of the model. Systems and methods described herein also provide for additional input data using an augmented tuft and taps inputs for the physics-informed neural network to generate the shear wall stress profile.