Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

A New Wake Model for Estimating Flow Velocity Distributions Around Offshore Circular Structures
Deqiang Tiana Zhong Lia Dangsheng Zhangb Liangbin Xua Honghai Fanc Leixiang Shenga Chaowei Lia Yushuang Zhangc
a. China National Offshore Oil Corporation Research Institute, Beijing, Chinab. CNPC Bohai Drilling Engineering Company Limited, Hebei, Chinac. China University of Petroleum (Beijing), Beijing, ChinaABSTRACT
Many offshore structures contain elements with cylindrical shape, suchas jacket, jack up and tension-leg platforms, marine pipelines andoffshore drilling and production risers, etc. Considerable efforts havebeen made in recent years on developing the theoretical wake model toensure the calculating results of current forces more accurate. However,these traditional models still have a few limitations which might lead tolarge errors in static or dynamic analyzing process. This study
developed a new effective wake model to estimate the wake velocity
distributions behind circular cylinder. The presented model was derived
based on Reichardt’s wake model for the time averaged wake velocity
distribution. It is a combination of using Tollmien’s first approximation
method and Goldstein’s second approximation method. Results indicatethat the correction works by this paper do not make much difference
when calculating the wake field at large distance. However, it will
make a significant difference for the wake field close to the cylinder.
The presented wake model is validated by comparing with publishedexperimental and numerical data. Comparison results show a goodreliability and stability whenever at far wake field or near wake field,
broadly extends the earlier findings.

constants
streamwise distanceytransverse distanceCDdrag coefficientFDdrag on cylinder

ddiameter of cylinder

hlength of cylinderuv

Time-averaged streamwise wake velocity

udeficit velocity

u1

the first term of deficit velocity
the second term of deficit velocity

Time-averaged transverse wake velocity

v1

the n th term of deficit velocity
the first term of transverse velocity

v2

the second term of transverse velocityunρετκ1density of fluid
laminar kinematic viscosity of fluid
Time-averaged hydrostatic pressure
virtual kinematic viscosity
Empirical constantb
P ( x0 , y0 )the width of the mixing zone
any point in downstream wake areaυpINTRODUCTION
Flow over circular cylinder is a simple and useful model for many
applications concerning obstacles to flow. It has been investigated formany years by numerical and experimental method. Meanwhile, thetheoretical study of two-dimensional far-wake flow down stream of
circular cylinders has also attracted much attention of many scholars（Blevins,2005; Fu,2017; Huse, 1992; Reichardt, 1942; Schlichting,1930; Wu, 2002）. Trace back to 1930, two-dimensional wakes werefirst investigated by H. Schlichting in his presented thesis (Schlichting,1930). Schlichting’s investigation, which was based on Prandtl’smixing length hypothesis, was found to be in good agreement with theexperimental data that he obtained before. However, measurements
showed that Schlichting’s solution just constituted an approximation forNOMENCLATUREx

free-stream velocity

u2

KEY WORDS: Wake model, flow velocity, offshore circularstructure, deficit velocity, approximation methodεo, CU∞1894