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2025 | Book

CFD-Compatible RANS/LES Modeling of Transitional and Separated Flows

Authors: Jiakuan Xu, Min Chang, Junqiang Bai

Publisher: Springer Nature Singapore

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About this book

This book investigates in detail boundary layer transition-turbulence modeling methods, which is a hot research topic in fluid mechanics and aerospace engineering. It introduces detailed physical model construction ideas and extensive calculation examples, which will enable readers to learn how to choose the correct model to use, understand the whole process of physical model construction, and learn how to develop new models. Studies on transition-turbulence models have attracted engineers and scientists from various disciplines, such as aerospace engineering, wind energy, ocean engineering and engine engineering. Pursuing a holistic approach, the book establishes several classical/representative transition-turbulence models for engine internal and external flows, while emphasizing the importance of PDE transport equation establishment and local computation methods for non-local variables. It is intended for post-graduate students and researchers who are interested in computational fluid dynamics and transition-turbulence.modeling or aerodynamic shape design (laminar flow design and control).

Table of Contents

Frontmatter
Chapter 1. Introduction
Abstract
Boundary layer transition refers to the phenomenon where fluid shifts from laminar to turbulent flow, causing significant changes in wall friction forces, heat flux, and flight mechanical characteristics. Therefore, accurate transition prediction is crucial for research in aerospace, wind engineering, and related fields. This book will provide comprehensive coverage of development methodologies for subsonic/transonic boundary layer transition models, formulation of Very Large Eddy Simulation (VLES) approaches applicable to separated flows and construction techniques for transitional-separated flow hybrid models.
Jiakuan Xu, Min Chang, Junqiang Bai
Chapter 2. The Development and Enhancement of the Very Large Eddy Simulation Method
Abstract
This chapter provides a detailed analysis of the inherent limitations in traditional Very Large Eddy Simulation (VLES) methods. To address these issues, a targeted improvement strategy is proposed, incorporating a novel filtering scale function and a boundary layer protection function. These advancements aim to mitigate grid-induced separation and modeled stress depletion phenomena. By enabling accurate delineation between Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) regions while reducing grid-scale sensitivity, the enhanced approach significantly improves the VLES method’s predictive accuracy for fully turbulent separated flows.
Jiakuan Xu, Min Chang, Junqiang Bai
Chapter 3. Prediction Model for Bypass Transition and Separation-Induced Transition
Abstract
This chapter presents a novel indicator capable of characterizing pressure gradients and sensing turbulent fluctuation intensity at the boundary layer edge, while satisfying Galilean invariance. Leveraging direct numerical simulation (DNS) data, prediction models for both bypass transition and separation-induced transition are developed in RANS framework. The accuracy and universality of these models have been rigorously validated through extensive wind tunnel experiments on benchmark test cases.
Jiakuan Xu, Min Chang, Junqiang Bai
Chapter 4. Transition Prediction Model Considering the Effects of Surface Roughness
Abstract
Surface roughness effects on aircraft walls significantly influence boundary layer transition locations, thereby profoundly affecting aerodynamic performance and heat transfer characteristics. This chapter proposes a roughness amplification factor transport equation and establishes transition criteria accounting for roughness effects based on wind tunnel experimental data. Coupled with an intermittency factor transport equation, these components form a comprehensive transition prediction model that systematically incorporates wall roughness effects.
Jiakuan Xu, Min Chang, Junqiang Bai
Chapter 5. Modeling and Application of the VLES Method Considering the Influence of Transition and Surface Roughness
Abstract
This chapter integrates the roughness-transition model with the VLES methodology, developing a hybrid prediction model for transition-separated flows applicable to rough walls. Validated through representative test cases including the V103 compressor cascade and Pak-B turbine blade, the proposed approach achieves simulation accuracy comparable to LES methods while demonstrating significantly reduced computational costs.
Jiakuan Xu, Min Chang, Junqiang Bai
Chapter 6. Summary and Future Prospects
Abstract
This chapter summarizes the key content of the entire book, distills its innovative contributions, and provides perspectives on future research directions.
Jiakuan Xu, Min Chang, Junqiang Bai
Backmatter
Metadata
Title
CFD-Compatible RANS/LES Modeling of Transitional and Separated Flows
Authors
Jiakuan Xu
Min Chang
Junqiang Bai
Copyright Year
2025
Publisher
Springer Nature Singapore
Electronic ISBN
978-981-9668-86-1
Print ISBN
978-981-9668-85-4
DOI
https://doi.org/10.1007/978-981-96-6886-1

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