Sensitivity of incipient particle motion to fluid flow penetration depth within a packed bed

SedimentologyVolume 57, Issue 2 p. 418-428 Sensitivity of incipient particle motion to fluid flow penetration depth within a packed bed BENJAMIN A. YERGEY, BENJAMIN A. YERGEY Mechanical Engineering Department, Bucknell University, 701 Moore Avenue, Lewisburg, PA 17837, USA (E-mail: [email protected])Search for more papers by this authorMARIA-LAURA BENINATI, MARIA-LAURA BENINATI Mechanical Engineering Department, Bucknell University, 701 Moore Avenue, Lewisburg, PA 17837, USA (E-mail: [email protected])Search for more papers by this authorJEFFREY S. MARSHALL, JEFFREY S. MARSHALL School of Engineering, University of Vermont, Burlington, VT 05405, USASearch for more papers by this author BENJAMIN A. YERGEY, BENJAMIN A. YERGEY Mechanical Engineering Department, Bucknell University, 701 Moore Avenue, Lewisburg, PA 17837, USA (E-mail: [email protected])Search for more papers by this authorMARIA-LAURA BENINATI, MARIA-LAURA BENINATI Mechanical Engineering Department, Bucknell University, 701 Moore Avenue, Lewisburg, PA 17837, USA (E-mail: [email protected])Search for more papers by this authorJEFFREY S. MARSHALL, JEFFREY S. MARSHALL School of Engineering, University of Vermont, Burlington, VT 05405, USASearch for more papers by this author First published: 14 January 2010 https://doi.org/10.1111/j.1365-3091.2009.01088.xCitations: 10Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract A discrete element method is applied to a three-dimensional analysis related to sediment entrainment on a micro-scale. Sediment entrainment is the process by which a fluid medium accelerates particles from rest and advects them upward until they are either transported as bedload or suspended by the flow. Modelling of the entrainment process is a critically important aspect for studies of erosion, pollutant resuspension and transport, and formation of bedforms in environmental flows. Previous discrete element method studies of sediment entrainment have assumed the flow within the particle bed to be negligible and have only allowed for the motion of the topmost particles. At the same time, micro-scale experimental studies indicate that there is a small slip of the fluid flow at the top of the bed, indicating the presence of non-vanishing fluid velocity within the topmost bed layers. The current study demonstrates that the onset of particle incipient motion, which immediately precedes particle entrainment, is highly sensitive to this small fluid flow within the topmost bed layers. Using an exponential decay profile for the inner-bed fluid flow, the discrete element method calculations are repeated with different fluid penetration depths within the bed for several small particle Reynolds numbers. For cases with slip velocity corresponding to that observed in previous experiments with natural sediment, the predicted particle velocity is found to be a few percent of the fluid velocity at the top of the viscous wall layer, which is a reasonable range of velocities for observation of incipient particle motion. This method for prescribing the fluid flow within the particle bed allows for the current discrete element method to be extended in future studies to the analysis of sediment entrainment under the influence of events such as turbulent bursting. Additionally, predictions for the slip velocities and fluid flow profile within the bed suggest the need for further experimental studies to provide the data necessary for additional improvement of the discrete element method models. Citing Literature Volume57, Issue2February 2010Pages 418-428 RelatedInformation