Volume 12 Issue 4
Dec.  2019
Turn off MathJax
Article Contents
Article Navigation >  Water Science and Engineering  > 2019  >  12(4): 319-329
Naveed Anjum, Norio Tanaka. 2019: Numerical investigation of velocity distribution of turbulent flow through vertically double-layered vegetation. Water Science and Engineering, 12(4): 319-329. doi: 10.1016/j.wse.2019.11.001
Citation: Naveed Anjum, Norio Tanaka. 2019: Numerical investigation of velocity distribution of turbulent flow through vertically double-layered vegetation. Water Science and Engineering, 12(4): 319-329. doi: 10.1016/j.wse.2019.11.001
shu

Numerical investigation of velocity distribution of turbulent flow through vertically double-layered vegetation

doi: 10.1016/j.wse.2019.11.001

  • a Graduate School of Science and Engineering, Saitama University,  Saitama 338-8570, Japan

  • b International Institute for Resilient Society, Saitama University,  Saitama 338-8570, Japan

More Information
  • Corresponding author: Norio Tanaka
  • Received Date: 2019-04-13
  • Rev Recd Date: 2019-09-26
    Abstract
  • The velocity structures of flow through vertically double-layered vegetation (VDLV) as well as single-layered rigid vegetation (SLV) were investigated computationally with a three-dimensional (3D) Reynolds stress turbulence model, using the computational fluid dynamics (CFD) code FLUENT. The detailed velocity distribution was explored with a varying initial Froude number (Fr), with consideration of the steady subcritical flow conditions of an inland tsunami. In VDLV flows, the numerical model successfully captured the inflection point in the profiles of mean streamwise velocities in the mixing-layer region around the top of short submerged vegetation. An upward and downward movement of flow occurred at the positions located just behind the tall and short vegetation, respectively. Overall, higher streamwise velocities were observed in the upper vegetation layer due to high porosity, with  = 98% (sparse vegetation, where  is the porosity), as compared to those in the lower vegetation layer, which had comparatively low porosity, with = 91% (dense vegetation). A rising trend of velocities was found as the flow passed through the vegetation region, followed by a clear sawtooth distribution, as compared to the regions just upstream and downstream of vegetation, where the flow was almost uniform. In VDLV flows, a rising trend in the flow resistance was observed with the increase in the initial Froude number, i.e., Fr = 0.67, 0.70, and 0.73. However, the flow resistance in the case of SLV was relatively very low. The numerical results also show the flow structures within the vicinity of short and tall vegetation, which are difficult to attain through experimental measurements.

     

    • FullText(HTML)
  • loading
    • References(33)
  • Anjum, N., Ghani, U., Pasha, G.A., Rashid, M.U., Latif, A., Rana, M.Z.Y., 2018a. Reynolds stress modeling of flow characteristics in a vegetated rectangular open channel. Arabian Journal for Science and Engineering, 43(10), 5551–5558. https://doi.org/10.1007/s13369-018-3229-8.
    Anjum, N., Ghani, U.,  Pasha, G.A., Latif, A., Sultan, T., Ali, S., 2018b. To investigate the flow structure of discontinuous vegetation patches of two vertically different layers in an open channel. Water, 10(1). https://doi.org/10.3390/w10010075.
    Anjum, N., Tanaka, N. 2019. Study on the flow structure around discontinued vertically layered vegetation in an open channel. Journal of Hydrodynamics. https://doi.org/10.1007/s42241-019-0040-2.
    Barrios-Piña, H., Ramírez-León, H., Rodríguez-Cuevas, C., Couder-Castañeda, C. 2014. Multilayer numerical modeling of flows through vegetation using a mixing-length turbulence model. Water, 6(7), 2084–2103. https://doi.org/10.3390/w6072084.
    Finnigan, J. 2000. Turbulence in plant canopies. Annual Review of Fluid Mechanics, 32(1), 519–571. https://doi.org/10.1146/annurev.fluid.32.1.519.
    Ghani, U., Anjum, N., Pasha, G.A., Ahmad, M. 2019. Numerical investigation of the flow characteristics through discontinuous and layered vegetation patches of finite width in an open channel. Environmental Fluid Mechanics, 19(6), 1469–1495. https://doi.org/10.1007/s10652-019-09669-x.
    Ghisalberti, M., Nepf, H., 2005. Mass transport in vegetated shear flows. Environmental Fluid Mechanics, 5(6), 527–551. https://doi.org/10.1007/s10652-005-0419-1.
    Harada, K., Imamura, F., 2005. Effects of coastal forest on tsunami hazard mitigation: A preliminary investigation. In: Satake, K., ed., Tsunamis: Case Studies and Recent Development. Springer, Dordrecht, pp. 279–292. https://doi.org/10.1007/1-4020-3331-1_17.
    Huai, W., Wang, W., Hu, Y., Zeng, Y., Keith, Z.Y., 2014. Analytical model of the mean velocity distribution in an open channel with double-layered rigid vegetation. Advances in Water Resources, 69, 106–113. https://doi.org/10.1016/j.advwatres.2014.04.001.
    Iimura, K., Tanaka, N., 2012. Numerical simulation estimating effects of tree density distribution in coastal forest on tsunami mitigation. Ocean Engineering, 54, 223–232. https://doi.org/10.1016/j.oceaneng.2012.07.025.
    Kathiresan, K., Rajendran, N., 2005. Coastal mangrove forests mitigated tsunami, short note. Estuarine, Coastal and Shelf Science, 65(3), 601–606. https://doi.org/10.1016/j.ecss.2005.06.022.
    Lima, P.H.S., Janzen, J.G., Nepf, H.M., 2015. Flow patterns around two neighboring patches of emergent vegetation and possible implications for deposition and vegetation growth. Environmental Fluid Mechanics, 15(4), 881–898. https://doi.org/10.1007/s10652-015-9395-2.
    Liu, D., Diplas, P., Hodges, C.C., Fairbanks, J.D., 2010. Hydrodynamics of flow through double layer rigid vegetation. Geomorphology, 116(3-4), 286–296. https://doi.org/10.1016/j.geomorph.2009.11.024.
    Lopez, F., Garcia, M.H., 2001. Mean flow and turbulence structure of open-channel flow through non-emergent vegetation. Journal of Hydraulic Engineering, 127(5), 392–402. https://doi.org/10.1061/(ASCE)0733-9429(2001)127:5(392).
    Mori, N., Takahashi, T., The 2011 Tohoku Earthquake Tsunami Joint Survey Group, 2012. Nationwide post event survey and analysis of the 2011 Tohoku earthquake tsunami. Coastal Engineering Journal, 52(1),  1250001-1–1250001-27. https://doi.org/10.1142/S0578563412500015.
    Pasha, G.A., Tanaka, N., 2017. Undular hydraulic jump formation and energy loss in a flow through emergent vegetation of varying thickness and density. Ocean Engineering, 141, 308–325. https://doi.org/10.1016/j.oceaneng.2017.06.049.
    Pu, J.H., Hussain, A., Guo, Y.K., Vardakastanis, N., Hanmaiahgari, P.R., Lam, D., 2019. Submerged flexible vegetation impact on open channel flow velocity distribution: An analytical modelling study on drag and friction. Water Science and Engineering, 12(2), 121–128. https://doi.org/10.1016/j.wse.2019.06.003. 
    Rashedunnabi, A.H.M., Tanaka, N., 2018. Physical modelling of tsunami energy reduction through vertically two layered rigid vegetation. In: Proceedings of the 12th International Symposium on Ecohydraulics. Tokyo, pp.1-10.
    Righetti, M., Armanini, A., 2002. Flow resistance in open channel flows with sparsely distributed bushes. Journal of Hydrology, 269(1-2), 55–64. https://doi.org/10.1016/S0022-1694(02)00194-4.
    Roulund, A., Sumer, B.M., Freds?e, J., Michelsen, J., 2005. Numerical and experimental investigation of flow and scour around a circular pile. Journal of Fluid Mechanics, 534, 351-401. https://doi.org/10.1017/S0022112005004507.
    Shuto, N. 1987. The effectiveness and limit of tsunami control forests. Coastal Engineering in Japan, 30(1), 143–153. https://doi.org/10.1080/05785634.1987.11924470.
    Singh, P., Rahimi, H.R. Tang, X., 2019. Parameterization of the modeling variables in velocity analytical solutions of open-channel flows with double-layered vegetation. Environmental Fluid Mechanics, 19(3), 765–784. https://doi.org/10.1007/s10652-018-09656-8.
    Takemura, T., Tanaka, N., 2007. Flow structures and drag characteristics of a colony-type emergent roughness model mounted on a flat plate in uniform flow. Fluid Dynamics Research, 39(9-10), 694–710. https://doi.org/10.1016/j.fluiddyn.2007.06.001.
    Tanaka, N., Sasaki, Y., Mowjood, M.I.M., Jinadasa, K.B.S.N., 2007. Coastal vegetation structures and their functions in tsunami protection: Experience of the recent Indian Ocean tsunami. Landscape and Ecological Engineering, 3(1), 33–45. https://doi.org/10.1007/s11355-006-0013-9.
    Tanaka, N., Yagisawa, J., Sasaki, Y., 2012. Characteristic of damage due to tsunami propagation in river channels and overflow of their embankments in Great East Japan Earthquake. International Journal of River Basin Management, 10(3), 269-279. https://doi.org/10.1080/15715124.2012.694365.
    Tanaka, N., Yagisawa, J., Yasuda, S., 2013. Breaking pattern and critical breaking condition of Japanese pine trees on coastal sand dunes in huge tsunami caused by Great East Japan Earthquake. Natural Hazards, 65(1), 423–442. https://doi.org/10.1007/s11069-012-0373-4.
    Tanaka, N., Yasuda, S., Iimura, K., Yagisawa, J., 2014. Combined effects of coastal forest and sea embankment on reducing the washout region of houses in the Great East Japan tsunami. Journal of Hydro-Environment Research, 8(3), 270–280. https://doi.org/10.1016/j.jher.2013.10.001.
    Tanaka, N., Onai, A., 2017. Mitigation of destructive fluid force on buildings due to trapping of floating debris by coastal forest during the Great East Japan tsunami. Landscape and Ecological Engineering, 13(1), 131–144. https://doi.org/10.1007/s11355-016-0308-4.
    Wang, W., Huai, W.X., Gao, M., 2014. Computation of flow structure through double layer vegetation. In: Proceedings of Mathematical and Computational Methods in Science and Engineering. pp. 132–136.
    Wu, Z.Y., Jiang, C.B., Deng, B., Chen, J., Cao, Y.G., Li, L.J., 2018. Evaluation of numerical wave model for typhoon wave simulation in South China Sea. Water Science and Engineering, 11(3), 229–235. https://doi.org/10.1016/j.wse.2018.09.001.
    Yanagisawa, H., Koshimura, S., Goto, K., Miyagi, T., Imamura, F., Ruangrassamee, A., Tanavud, C., 2009. The reduction effects of mangrove forest on a tsunami based on field surveys at Pakarang Cape, Thailand and numerical analysis. Estuarine, Coastal and Shelf Science, 81(1), 27–37. https://doi.org/10.1016/j.ecss.2008.10.001.
    Zheng, J.H., Sang, S., Wang, J.C., Zhou, C.Y., Zhao, H.J., 2017a. Numerical simulation of typhoon-induced storm surge along Jiangsu coast, Part I: Analysis of tropical cyclone. Water Science and Engineering, 10(1), 2–7. https://doi.org/10.1016/j.wse.2017.03.004.
    Zheng, J.H., Wang, J.C., Zhou, C.Y., Zhao, H.J., Sang, S., 2017b. Numerical simulation of typhoon-induced storm surge along Jiangsu coast, Part II: Calculation of storm surge. Water Science and Engineering, 10(1), 8–16. https://doi.org/10.1016/j.wse.2017.03.011.
    • Relative Articles
    • Supplements(0)
    • Cited By
  • 加载中

Catalog

    通讯作者: 陈斌, bchen63@163.com
    • 1. 

      沈阳化工大学材料科学与工程学院 沈阳 110142

    1. 本站搜索
    2. 百度学术搜索
    3. 万方数据库搜索
    4. CNKI搜索
    Get Citation
    PDF
    XML

    Article Metrics

    Article views (407) PDF downloads(388) Cited by()
    Proportional views
    Related

    Copyright © 2009 Editorial office of Water Science and Engineering 苏ICP备12023610号-1

    Supported by: Beijing Renhe Information Technology Co. Ltd   support: info@rhhz.net

    /

    DownLoad:  Full-Size Img  PowerPoint
    Return
    Return