Non-Linear k-ϵ Model for Open-Channel Flows over Sand Ridges and Trough

doi:10.2112/1551-5036-52.SP1.33

Citations

PDF

Open Access

More filters

Journal Article•DOI•

Numerical investigation on the suitability of a fourth-order nonlinear k-ω model for secondary current of second type in open-channels

[...]

Mahdad Talebpour¹, Xiaofeng Liu¹•Institutions (1)

Pennsylvania State University¹

02 Jan 2019-Journal of Hydraulic Research

TL;DR: In this article, the authors evaluated a typical nonlinear fourth-order k-ω model and the associated roughness boundary condition for their suitability for simulating secondary current of the second kind in open-channels induced by roughness non-uniformity.

...read moreread less

Abstract: This study evaluated a typical nonlinear fourth-order k-ω model and the associated roughness boundary condition for their suitability for simulating secondary current of the second kind in open-channels induced by roughness non-uniformity. Three test cases were simulated: square duct flow, open-channel flow with uniformly roughened bed and smooth side walls, and open-channel flow over roughness patches. The nonlinear model and the roughness boundary condition performed relatively well for the first two cases where the corner effect was dominant. For the third case, with alternate roughness patches, strong pressure gradient was generated at the edge between adjacent patches and the secondary current was greatly over-predicted. Two remedial options were tested: increasing the roughness height for smooth walls to a reasonable value and smoothing the roughness transition with a hyperbolic tangent function. We found the first option works better and the second only marginally improves the results.

...read moreread less

15 citations

References

PDF

Open Access

More filters

Journal Article•DOI•

A calculation procedure for heat, mass and momentum transfer in three-dimensional parabolic flows

[...]

S.V. Patankar¹, D. B. Spalding¹•Institutions (1)

Imperial College London¹

01 Oct 1972-International Journal of Heat and Mass Transfer

TL;DR: In this article, a general, numerical, marching procedure is presented for the calculation of the transport processes in three-dimensional flows characterised by the presence of one coordinate in which physical influences are exerted in only one direction.

...read moreread less

5,946 citations

"Non-Linear k-ϵ Model for Open-Chann..." refers methods in this paper

...As the solution strategy, the SIMPLER algorithm proposed by Patankar and SPALDING (1972) was employed....
[...]

Book•

Turbulence in open-channel flows

[...]

Iehisa Nezu

01 Jan 1993

TL;DR: A review of open channel turbulence, focusing especially on certain features stemming from the presence of the free surface and the bed of a river, can be found in this paper, where the statistical theory of turbulence and coherent structures in open channel flows and boundary layers are discussed.

...read moreread less

Abstract: A review of open channel turbulence, focusing especially on certain features stemming from the presence of the free surface and the bed of a river. Part one presents the statistical theory of turbulence; Part two addresses the coherent structures in open-channel flows and boundary layers.

...read moreread less

1,446 citations

"Non-Linear k-ϵ Model for Open-Chann..." refers background or methods in this paper

...Notably, when SPEZIALE (1987)’s proposed CD = CE = 1.68 is used, the maximum magnitude of the secondary currents appears to be 2.6% of the streamwise maximum velocity, which is slightly smaller than the value of 3% observed in the laboratory experiments by NEZU and NAKAGAWA (1993)....
[...]
...In Figure 3(a), the data near the free surface appear to be overestimated because the magnitude of the secondary currents near the free surface is normally smaller than that near the bottom (NEZU and NAKAGAWA, 1993)....
[...]

Journal Article•DOI•

On nonlinear K-l and K-ε models of turbulence

[...]

Charles G. Speziale¹•Institutions (1)

Georgia Institute of Technology¹

01 May 1987-Journal of Fluid Mechanics

TL;DR: In this paper, a nonlinear K-l and K-e model is proposed to predict the normal Reynolds stresses in turbulent channel flow much more accurately than the linear model, and the nonlinear model is shown to be capable of predicting turbulent secondary flows in non-circular ducts.

...read moreread less

Abstract: The commonly used linear K-l and K-e models of turbulence are shown to be incapable of accurately predicting turbulent flows where the normal Reynolds stresses play an important role. By means of an asymptotic expansion, nonlinear K-l and K-e models are obtained which, unlike all such previous nonlinear models, satisfy both realizability and the necessary invariance requirements. Calculations are presented which demonstrate that this nonlinear model is able to predict the normal Reynolds stresses in turbulent channel flow much more accurately than the linear model. Furthermore, the nonlinear model is shown to be capable of predicting turbulent secondary flows in non-circular ducts - a phenomenon which the linear models are fundamentally unable to describe. An additional application of this model to the improved prediction of separated flows is discussed briefly along with other possible avenues of future research.

...read moreread less

644 citations

"Non-Linear k-ϵ Model for Open-Chann..." refers background or methods in this paper

...Since the standard k-ε model cannot account for non-isotropy of turbulence, the non-linear k-ε model proposed by SPEZIALE (1987) was used....
[...]
...SPEZIALE (1987) proposed CD = CE = 1.68 for internal flows without the free-surface effect....
[...]
...Notably, when SPEZIALE (1987)’s proposed CD = CE = 1.68 is used, the maximum magnitude of the secondary currents appears to be 2.6% of the streamwise maximum velocity, which is slightly smaller than the value of 3% observed in the laboratory experiments by NEZU and NAKAGAWA (1993)....
[...]
...The non-linear k-ε model by SPEZIALE (1987) estimates the Reynolds stresses in Eqs....
[...]

Journal Article•DOI•

Transportation of Suspended Sediment by Water

[...]

Vito A. Vanoni¹•Institutions (1)

California Institute of Technology¹

01 Jan 1946-Transactions of the American Society of Civil Engineers

TL;DR: In this paper, measurements of sediment and velocity distributions in a laboratory flume were made for various values of rate of flow, slope of channel, and size and amount of suspended load.

...read moreread less

Abstract: Measurements of the sediment and velocity distributions in a laboratory flume were made for various values of rate of flow, slope of channel, and size and amount of suspended load. The experimental...

...read moreread less

420 citations

"Non-Linear k-ϵ Model for Open-Chann..." refers background in this paper

...Cellular secondary currents have also been reproduced in laboratory experiments (VANONI, 1946; ALLEN, 1966; HINZE, 1973; GUNTER, 1971; IKEDA, 1981; HIRANO and OHMOTO, 1988; NEZU and NAKAGAWA, 1984, 1986; MCLEAN, 1981; MCLELLAND et al., 1999; MULLER and STUDERUS, 1979; WANG and CHENG, 2005, 2006)....
[...]

Journal Article•DOI•

Cellular Secondary Currents in Straight Conduit

[...]

Iehisa Nezu, Hiroji Nakagawa

01 Feb 1984-Journal of Hydraulic Engineering

TL;DR: In this paper, the authors investigated the turbulent structure of secondary currents in air conduit, considering an essential interaction between secondary currents and bed-form, longitudinal ridge elements were attached onto both lower and upper bottoms of the conduit, which simulated the longitudinal ridges and troughs of river bedform, i.e., sand ribbons.

...read moreread less

Abstract: An investigation of cellular secondary currents, i.e., three-dimensional flow patterns, is very important in hydraulic engineering because these currents might cause three-dimensional sediment distributions and bed configurations such as sand ribbons in straight rivers. It is, however, fairly difficult to measure secondary currents of water flows, even by making use of hot-film anemometers, because the velocity of secondary currents is within 5% of the mainstream velocity. Thus, on the basis of the hypothesis that the existence of free surface may not be an essential cause of secondary currents, the present study has investigated experimentally the turbulent structure of their currents in air conduit. Considering an essential interaction between secondary currents and bedform, longitudinal ridge elements were attached onto both lower and upper bottoms of the conduit, which simulated the longitudinal ridges and troughs of river bedform, i.e., sand ribbons. All three components of the velocity were measured accurately by hotwire anemometers. The structure of secondary currents was examined through the equations of mean flow vorticity and mean flow energy.

...read moreread less

130 citations

"Non-Linear k-ϵ Model for Open-Chann..." refers background or methods or result in this paper

...FLOWS OVER LONGITUDINAL BEDFORMS The developed numerical model can now be applied to two experimental cases of open-channel flows over longitudinal bedforms, reported by NEZU and NAKAGAWA (1984) and WANG and CHENG (2006)....
[...]
...It can be seen that the pattern of the simulated secondary currents is akin to that observed by NEZU and NAKAGAWA (1984). However, the maximum magnitude of the simulated secondary current vectors was about 2.3% of the maximum streamwise mean velocity, slightly smaller than the value (= 2.5%) observed by NEZU and NAKAGAWA (1984). Specifically, note that the downflows, compared with the measured data, were seriously underestimated by the model....
[...]
...%) observed by NEZU and NAKAGAWA (1984)....
[...]
...It can be seen that the pattern of the simulated secondary currents is akin to that observed by NEZU and NAKAGAWA (1984)....
[...]
...The mechanism initiating those currents has been investigated by researchers including NEZU and NAKAGAWA (1984), IKEDA (1981), COLOMBINI (1993), and COLOMBINI and PARKER (1995), but in none of these studies was it clearly demonstrated....
[...]

Non-Linear k-ϵ Model for Open-Channel Flows over Sand Ridges and Trough

Citations

References

"Non-Linear k-ϵ Model for Open-Chann..." refers methods in this paper

"Non-Linear k-ϵ Model for Open-Chann..." refers background or methods in this paper

"Non-Linear k-ϵ Model for Open-Chann..." refers background or methods in this paper

"Non-Linear k-ϵ Model for Open-Chann..." refers background in this paper

"Non-Linear k-ϵ Model for Open-Chann..." refers background or methods or result in this paper

Related Papers (5)