Rotating and swirling turbulence comprises an important class of flows, not only due to the complex physics that occur, but also due to their relevance to many engineering applications, such as combustion, cyclone separation, mixing, etc. In these types of flows, rotation strongly affects the characteristics and structure of turbulence. However, the underlying turbulent flow phenomena are complex and currently not well understood. The axially rotating pipe is an exemplary prototypical model problem that exhibits these complex turbulent flow physics. By examining the complex interaction of turbulent structures within rotating turbulent pipe flow, insight can be gained into the behavior of rotating flows relevant to engineering applications. Direct numerical simulations are conducted at a bulk Reynolds number up to Re_D = 19,000 with rotation numbers ranging from N = 0 to 3. Coherence analysis, including Proper Orthogonal Decomposition and Dynamic Mode Decomposition, are used to identify the relevant (highest energy) modes of the flow. Studying the influence of these modes on turbulent statistics (i.e. mean statistics, Reynolds stresses, turbulent kinetic energy, and turbulent kinetic energy budgets) allow for a deeper understanding of the effects of coherent turbulent flow structures in rotating flows.
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A Numerical Investigation of the Effects of Rotation on Turbulent Pipe Flows
In past experiments, simulations and theoretical analysis,
rotation has been shown to dramatically effect the
characteristics of turbulent flows, such as causing the mean
velocity profile to appear laminar, leading to an overall
drag reduction, as well as affecting the Reynolds stress tensor.
The axially rotating pipe is an exemplary prototypical
model problem that exhibits these complex turbulent flow
physics. For this flow, the rotation of the pipe causes a region
of turbulence suppression which is particularly sensitive
to the rotation rate and Reynolds number. The physical
mechanisms causing turbulence suppression are currently
not wellunderstood, and a deeper understanding of these
mechanisms is of great value for many practical examples
involving swirling or rotating flows, such as swirl generators,
wingtip vortices, axial compressors, hurricanes, etc.
In this work, Direct Numerical Simulations (DNS) of
rotating turbulent pipe flows are conducted at moderate
Reynolds numbers (Re=5300, 11,700, and 19,000) and rotation
numbers of N=0 to 3. The main objectives of this
work are to firstly quantify turbulence suppression for rotating
turbulent pipe flows at different Reynolds numbers as
well as study the effects of rotation on turbulence by analyzing
the characteristics of the Reynolds stress tensor and the
production and dissipation terms of the turbulence budgets.
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 Award ID(s):
 1706346
 NSFPAR ID:
 10317256
 Date Published:
 Journal Name:
 11th International Symposium on Turbulence and Shear Flow Phenomena (TSFP11)
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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