Turbulent spots in hypersonic transitional planar and axisymmetric boundary layers

Fuente: arXiv
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Main Authors: Bajpai, Ankit, Gopalan, Jagadeesh
Format: Preprint
Published: 2026
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author Bajpai, Ankit
Gopalan, Jagadeesh
author_facet Bajpai, Ankit
Gopalan, Jagadeesh
contents Experiments were conducted to investigate characteristics of turbulent spots formed in transitional boundary layers developed over a flat plate and an axisymmetric cone placed in similar hypersonic freestream environment of Mach number 5.85. The freestream Reynolds number in the present work varied between $3.0-6.0\times10^6$/m. Heat transfer measurement along the surface of both the test models was used to ascertain the state of boundary layer and to calculate the intermittency associated with transitional boundary layer. Turbulent spots generated in the transitional boundary layer were characterized in terms of their leading-trailing edge velocities, their streamwise length scales and their generation rates on both the test models. Leading edge of the turbulent spots developed over both the test models were found to be convecting at a speed equivalent to 90\% of the boundary layer edge speed. The trailing edge of the spots developed on a planar boundary layer traversed at a lower speed than its axisymmetric counterpart. Streamwise length scales of a turbulent spot developed in a planar boundary layer grew at a higher rate when compared with axisymmetric boundary layer. Turbulent spot generation rates for both planar and axisymmetric boundary layers was found to be in the range of $1000000-3000000$ spots/m/s.
format Preprint
id arxiv_https___arxiv_org_abs_2601_08795
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Turbulent spots in hypersonic transitional planar and axisymmetric boundary layers
Bajpai, Ankit
Gopalan, Jagadeesh
Fluid Dynamics
Experiments were conducted to investigate characteristics of turbulent spots formed in transitional boundary layers developed over a flat plate and an axisymmetric cone placed in similar hypersonic freestream environment of Mach number 5.85. The freestream Reynolds number in the present work varied between $3.0-6.0\times10^6$/m. Heat transfer measurement along the surface of both the test models was used to ascertain the state of boundary layer and to calculate the intermittency associated with transitional boundary layer. Turbulent spots generated in the transitional boundary layer were characterized in terms of their leading-trailing edge velocities, their streamwise length scales and their generation rates on both the test models. Leading edge of the turbulent spots developed over both the test models were found to be convecting at a speed equivalent to 90\% of the boundary layer edge speed. The trailing edge of the spots developed on a planar boundary layer traversed at a lower speed than its axisymmetric counterpart. Streamwise length scales of a turbulent spot developed in a planar boundary layer grew at a higher rate when compared with axisymmetric boundary layer. Turbulent spot generation rates for both planar and axisymmetric boundary layers was found to be in the range of $1000000-3000000$ spots/m/s.
title Turbulent spots in hypersonic transitional planar and axisymmetric boundary layers
topic Fluid Dynamics
url https://arxiv.org/abs/2601.08795