Experimental Analysis of Velocity Distribution in a Coarse-Grained Debris Flow: A Modified Bagnold’s Equation
Today, Bagnold’s theory is still applied to gravity-driven flows under the assumption of uniform sediment concentration. This study presents findings of flume experiments conducted to investigate the velocity and concentration distributions within the debris body by using high-resolution images. The...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-05-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/12/5/1415 |
| _version_ | 1797567933285662720 |
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| author | Donatella Termini Antonio Fichera |
| author_facet | Donatella Termini Antonio Fichera |
| author_sort | Donatella Termini |
| collection | DOAJ |
| description | Today, Bagnold’s theory is still applied to gravity-driven flows under the assumption of uniform sediment concentration. This study presents findings of flume experiments conducted to investigate the velocity and concentration distributions within the debris body by using high-resolution images. The analysis has shown that the concentration and mobility of grains vary along the depth. A linear law to interpret the grains concentration distribution, starting from the knowledge of the packing concentration and of the surface concentration, Cs, has been identified. By considering such a law, modified expressions of the Bagnold’s number and the velocity in stony-type debris flows are also presented. By using these expressions, three regimes of motion have been identified along the depth, and the velocity profile within the debris body is determined as a function of the parameter Cs. It has been verified that the velocity profiles estimated by using the modified equation compare well (mean square error less than 0.1) with the literature’s measured profiles when Cs is correctly measured or estimated. Results of cutting tests, conducted for a sample of the used material, have also allowed us to verify that Cs could be determined as a function of the static friction angle of the material. |
| first_indexed | 2024-03-10T19:48:13Z |
| format | Article |
| id | doaj.art-fd46f04de4574287a9a002d4359d25e2 |
| institution | Directory Open Access Journal |
| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-10T19:48:13Z |
| publishDate | 2020-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Water |
| spelling | doaj.art-fd46f04de4574287a9a002d4359d25e22023-11-20T00:37:41ZengMDPI AGWater2073-44412020-05-01125141510.3390/w12051415Experimental Analysis of Velocity Distribution in a Coarse-Grained Debris Flow: A Modified Bagnold’s EquationDonatella Termini0Antonio Fichera1Department of Engineering, University of Palermo, 90128 Palermo, ItalyFaculty of Engineering, University Enna Kore, 94100 Enna, ItalyToday, Bagnold’s theory is still applied to gravity-driven flows under the assumption of uniform sediment concentration. This study presents findings of flume experiments conducted to investigate the velocity and concentration distributions within the debris body by using high-resolution images. The analysis has shown that the concentration and mobility of grains vary along the depth. A linear law to interpret the grains concentration distribution, starting from the knowledge of the packing concentration and of the surface concentration, Cs, has been identified. By considering such a law, modified expressions of the Bagnold’s number and the velocity in stony-type debris flows are also presented. By using these expressions, three regimes of motion have been identified along the depth, and the velocity profile within the debris body is determined as a function of the parameter Cs. It has been verified that the velocity profiles estimated by using the modified equation compare well (mean square error less than 0.1) with the literature’s measured profiles when Cs is correctly measured or estimated. Results of cutting tests, conducted for a sample of the used material, have also allowed us to verify that Cs could be determined as a function of the static friction angle of the material.https://www.mdpi.com/2073-4441/12/5/1415debris flowsflow velocitysediment concentrationprevision |
| spellingShingle | Donatella Termini Antonio Fichera Experimental Analysis of Velocity Distribution in a Coarse-Grained Debris Flow: A Modified Bagnold’s Equation Water debris flows flow velocity sediment concentration prevision |
| title | Experimental Analysis of Velocity Distribution in a Coarse-Grained Debris Flow: A Modified Bagnold’s Equation |
| title_full | Experimental Analysis of Velocity Distribution in a Coarse-Grained Debris Flow: A Modified Bagnold’s Equation |
| title_fullStr | Experimental Analysis of Velocity Distribution in a Coarse-Grained Debris Flow: A Modified Bagnold’s Equation |
| title_full_unstemmed | Experimental Analysis of Velocity Distribution in a Coarse-Grained Debris Flow: A Modified Bagnold’s Equation |
| title_short | Experimental Analysis of Velocity Distribution in a Coarse-Grained Debris Flow: A Modified Bagnold’s Equation |
| title_sort | experimental analysis of velocity distribution in a coarse grained debris flow a modified bagnold s equation |
| topic | debris flows flow velocity sediment concentration prevision |
| url | https://www.mdpi.com/2073-4441/12/5/1415 |
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