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بررسی عددی فراسنجه های هیدرولیکی جریان غلیظ در اثر انحنای بدنه کانال | ||
| تحقیقات مهندسی سازه های آبیاری و زهکشی | ||
| دوره 22، شماره 82، اردیبهشت 1400، صفحه 103-120 اصل مقاله (1.18 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22092/idser.2021.354303.1471 | ||
| نویسندگان | ||
| محمد حسینی* 1؛ محمد هادی فتاحی2 | ||
| 1گروه مهندسی عمران، مرکز قیروکارزین، دانشگاه آزاد اسلامی، قیروکارزین، ایران | ||
| 2گروه مهندسی عمران، واحد مرودشت، دانشگاه آزاد اسلامی، مرودشت، ایران | ||
| چکیده | ||
| جریان های غلیظ گونه ای از جریان های ثقلی هستند که اختلاف کمی در دانسیته سیال محیطی دارند و همواره با درون آمیختگی با سیال محیطی همراه اند. در این تحقیق، سعی شده است که با استفاده از نرم افزار دینامیک سیالات محاسباتی به خصوصیات جریان غلیظ در انحنای کانال پرداخته شود. سه مدل با انحنای 180 درجه و انحنای سینوسی محدود و سینوسی سیلاب دشتی شبیه سازی شده است. با تغییر عدد فرود، شیب و غلظت ورودی، جریان غلیظ مدل سازی برای تمامی مدل ها صورت گرفت. هدف از این مطالعه تاثیر انحنا بر خصوصیات هیدرولیکی جریان چگال است. نتایج بررسی ها نشان داد مدل آشفتگی بهینه برای تمامی مدل ها، مدل k-ε از نوع RNG است. افزایش شیب کف کانال از 2/0 درصد به 2درصد موجب کاهش ضخامت جریان گل آلود در طول کانال می شود، که در نتیجه آن سرعت جریان افزایش نشان می دهد. با افزایش عدد فرود ورودی از 22/1 به 8 ، در مدل با انحنای 180 درجه به ترتیب الگوی پروفیل غلظت نسبت به مدل های سینوسی محدود وسیلاب دشتی به میزان 19درصد و 3/21درصد کاهش می یابد، داده های ریچاردسون و شدت اختلاط در مدل با انحنای 180 درجه نسبت به مدل آزمایشگاهی 10درصد افزایش یافتند. با بررسی کلی هر سه مدل عدد ریچاردسون نسبت به شدت اختلاط، ارتباط معناداری با ضریب 71/0 نشان داده است. همچنین با افزایش شدت اختلاط و غلظت جریان، اعداد رینولدز بیشتر و جریان آشفته تر می شود و عدد ریچاردسون کاهش یابد. | ||
| کلیدواژهها | ||
| جریان غلیظ؛ دینامیک سیالات محاسباتی؛ مدل k-&epsilon؛ از نوع RNG؛ شدت اختلاط؛ عدد ریچاردسون | ||
| عنوان مقاله [English] | ||
| Numerical Investigation of Density Current Hydraulic Parameters due to the Curvature of the Channel Body | ||
| نویسندگان [English] | ||
| mohammad hosseini1؛ mohammad hadi fattahi2 | ||
| 1Department of Civil Engineering, Ghirokarzin Center, Islamic Azad University, Ghirokarzin, Iran. | ||
| 2Department of Civil Engineering, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran | ||
| چکیده [English] | ||
| Numerical Investigation of Density Flow Hydraulic Parameters due to the Curvature of the Channel Body Introduction Density difference causes density flow. Density flow is the the movement of the forehead, body, and tail of the heavy fluid into the ambient flow, and the buoyancy or gravity force causes the drive force. The movement of dense current under clear water creates a shear layer at the interface between clear water and density fluid. Therefore, at the interface, many cuts and vortices are created and this causes the entrainment of smooth water and density flow, which reduces the amount of density difference and the buoyancy force. Hosseini & Fattahi (2020) showed that the variations in the waterway shape causes higher velocity of density flow and decreases the flow thickness. Also, increasing the density of density flow, increases the maximum velocity in velocity profiles. This increase in the maximum velocity of the density flow is more pronounced in streams with higher inlet flow. The velocity profile patterns in the wall and jet area of the density flow body are influenced by the flow regime. Materials and Methods In this research, the density flow is illustrated in 3 different models according to Figure 1. The opening rate of the density flow valve is considered to be 1 cm. In this research, we have tried to show the effect of curvature at 180 ° bend and sinusoidal shape restricted channel and the flood plain. In this simulation the channel with 4 different longitudinal slopes, 0.002, 0.005, 0.008 and 0.02, are modeled and also 4 different densities, 0.00667, 0.00727, 0.00859 and 0.01 g / cm3, and 4 f Froude numbers, 1.2, 3, 5 and 8, have been used. Moreover six different mesh gridding for the flood plain and six different mish gridding for the channel are considered. it should be mentioned that 6 types of turbulence models ( The k-e model (standard, RNG, investigable), the kw model (standard, SST) and the RSM model (linear strain-pressure) are used. Results and Discussion Four types of networks were selected for finite channel with sinusoidal curvature. Figure (3) compares the different mesh gridding with the tested mesh and it was observed that in the range close to the bed, at high speeds, meshes with dimensions of 60 × 20 × 140 are very close to the experimental model developed by Hosseini & Fattahi (2020). Also, considering all 3 optimal models for turbulence models, k-ε models can be considered more optimal than k-ω and RSM models. The effects of the increasing slope of the flume bed in the wall area is more tangible than in the jet area while Froude number and input density are the same. On the other hand, increasing the slope of the channel bed from 0.2% to 2%, reduces the density flow thickness along the channel. As a result, the flow velocity shows an increase in the density flow which causes the growth of the drive force and will increase the turbulent flow velocity by increasing the inlet Froude number from 1.22 to 8. In all laboratory data, the density current concentration profile in the jet area shows a higher dispersion of 47% than the wall area. By increasing the slope of the channel from 0.2% to 2%, the dispersion rate increases by 65%. Richardson data and entrainment ratio in model No.1 increased by 10% compared to the experimental model and also these data increased by 19% in model No.2 compared to the experimental model. Conclusion In this research, we tried to simulate the three-dimensional density flow in models with 180 degree bend and limited sinusoidal curvature as well as sinusoidal patterns with plain flood. Also, the most optimal computational mesh, turbulence model, slope, density and Froude number are investigated as long as the studies include the depth profiles of velocity, density, turbulence, etc. in a situation where the channels are curved. Moreover, by increasing the number of Froude numbers from 1.22 to 8, due to model number 1 with 180 degree curvature, the pattern of density profile decreases by 19% and 21.3% compared to models number 2 and 3, respectively. Also, in all laboratory data, the density current concentration profile in the jet area shows a higher dispersion of 47% than the wall area. With increasing the slope of the channel from 0.2% to 2%, the dispersion rate increases by 65%. Richardson number has established a significant relationship with the entrainment ratio, which has a correlation of 0.71. Also the numerical entrainment ratio (for all three models) increased by 4.4% compared to the experimental model. Acknowledgments We would like to thank Water and Hydraulic Laboratory of Shiraz University for their effective cooperation. Keywords Computational fluid dynamics, K-ε model of RNG type, Entrainment ratio, Richardson number | ||
| کلیدواژهها [English] | ||
| Density current, Computational fluid dynamics, K-&epsilon, model of RNG type, Entrainment ratio, Richardson number | ||
| مراجع | ||
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Altinakar, M. S., Graf, W. H, & Hopfinger, E. J. (1990). Weakly Depositing Tubidity Current on Small Slopes. Journal of Hydraulic research, 28(1),55-80 Asghari Pari, S.A., Kashefipour, S.M, & Ghomeshi, M. (2017). An experimental study to determine the obstacle height required for the control of subcritical and supercritical gravity currents. European Journal of Environmental and Civil Engineering. 21(9): 1080–1092. Bahrami, H. Ghomeshi, M. Kashefipor, S.M. & Salehi, S.A. (2017). Investigating the characteristics of the density current due to changes in the flow regime. Journal of Marine Science and Thechnology. 16(1): 112-121. Bahrami, H. Ghomeshi, M. Kashefipor, S.M. & Salehi, S.A. (2019). Investigation of the effect of various factors on density currents entrainment. Journal of Marine Science and Thechnology. 18(1): 1-9. Carrillo, J., Castillo, L., Marco, F., & Garcia, J. (2020). Experimental and Numerical Analysis of Two-Phase Flows in Plunge Pools” Journal of Hydraulic Engineering, 146(6),4-11. Choi, S. U, & Garcia, M. H. (2002). K-ε turbulence modeling of density currents developing two dimensionally on a slope. J. Hydraul. Eng, 128(1), 55-63 Diaz. B, Castanedo. S, Palomar. P, Henno. F. (2018). Modeling Nonconfined Density Currents Using 3D Hydrodynamic Models. Journal of Hydrualic Engineering, 145(3), 55-72 Firoozabadi,B & Mehdizadeh,A.(2009). Simulation of a Density Current Turbulent Flow Employing Different RANS Models: A Comparison Study. Sharif University of Technology , 16(1),53-63. Garcia. M, (1993). “Hydraulic Jumps in Sediment-Driven Bottom Currents”. J. Hydraul. Engrg. 119(10), 1094–1173. Goodarzi, D., Sookhak, K., Khavasi, E., & Abolfathi, S. (2020). Large eddy simulation of turbidity currents in a narrow channel with different obstacle configurations. Scientific Reports, 10(1), 45-58. Hosseini, M. Fattahi, M, H. & Eslamian, S. (2020). Experimental Analytical Study on Fractal Behaviors of the Density Current. Iranian Journal of Science and Technology, Transactions of Civil Engineering, 45(2), 40-57. Hosseini, M. Fattahi, M, H. & Eslamian, S. (2020). Experimental Investigation and Dynamic Fractal and Multi-fractal Analysis of the Density Current Patterns. Water Resource Engineering, 13(2), 81-98. Hosseini, M. Fattahi, M, H. & Eslamian, S. (2020). Experimental Study of Hydraulic Parameters in Density Current Due to Channel Constriction. Journal of Hydraulics, 15(3), 47-59. Hosseini, M. Fattahi, M, H. & Eslamian, S. (2021). Experimental investigation of density current patterns using dynamic fractal analysis. International Journal of Sediment Research, 36(1), 165-176. Imran, J & Kassem, A. (2004). Three-dimensional modeling of density current. II. Flow in sinuous confined and unconfined channels. Journal of Hydraulic Research, 42(6), 591–602 Imran, J., Parker, G. & Pirmez, C. (2001). A Nonlinear Model of Flow in Meandering Submarine and Subaerial Channels”. J. Fluid Mech. 400, 295–331 Kubo, y. (2004). Experimental and numerical study of topographic effects on deposition from two- dimensional, particle-driven density currents. Sedimentary Geology., 164(1), 311-326. Mauti, G., Stolle, J., Takabatake, T., Nistor, L., Goseberg, N., & Mohammadian, A., (2020). Experimental Investigation of Loading due to Debris Dams on Structures” Journal of Hydraulic Engineering, 146(5). 92-113. Peakall, J & Keevil,G. (2006). Flow structure in sinuous submarine channels: Velocity and turbulence structure of an experimental submarine channel, Journal of Marine Geology, 229(1) , 241–257 Peakall,J & Ashworth,P. (2007).Meander-Bend evolution, Alluvial architecture, and the role of cohesion in sinuous river channels: a flume study. Journal of Sedimentary Research, 77(1), 197–212 Pittaluga, M. & Imran, J. (2014). A simple model for vertical profiles of velocity and suspended sediment concentration in straight and curved submarine channels. Journal of Geophysical Research: Earth Surface. 119(2): 483-503. Pyler,, D & Tomasso,M .(2012).Flow processes and sedimentation associated with erosion and filling of sinuous submarine channels. Journal of GSA,40(2), 143-146 Shringarpure, M. Cantero, M.I, & Balachandar, S. (2016). Analysis of turbulence suppression in sediment-laden saline currents. Procedia Engineering. 126(10): 16-23. Straub, K,M & Mohring ,D.(2011).Quantifying the influence of channel sinuosity on the depositional mechanics of channelized turbidity currents: A laboratory study. Journal of Marine and Petroleum Geology, 28(1), 744-760. Wu, C. S, & Dai, A. (2019). Experiments on two-layer stratified gravity currents in the slumping phase, Journal of Hydraulic Research, 57(4). 115-131. | ||
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