Nonspherical particle suspensions in wall turbulence
MetadataShow full item record
In the present PhD thesis, we investigate the dynamics of small non-spherical particles suspended in a fully developed turbulent channel flow. Non-spherical particles are approximated as axisymmetric spheroidal and triaxial ellipsoidal particles, which are characterized by their inertia and shape. As a starting point, the rotational dynamics of an inertial oblate spheroidal particle suspended in a creeping linear shear flow is investigated, which is later used in interpreting the results obtained in complex turbulent flows. The three-dimensional turbulent flow field is obtained from the Navier-Stokes equations by means of direct numerical simulation in an Eulerian reference frame. The particles are tracked using Lagrangian point particle approach. Existing methodology to simulate the prolate spheroidal particles in wall-bounded turbulent channel flow is extended to investigate the dynamics of oblate spheroidal particles and triaxial ellipsoidal particles. The effects of particle inertia, particle shape, and fluid shear on particle rotation and orientation are reported with respect to both fluid and particle reference frame. Particles at the channel center and near the wall show different rotation patterns and surprisingly different effects of particle inertia. Finally, we report the systematic investigation of the gravity force effects on the dynamics of prolate spheroidal particles.
Has partsArticle 1. Challabotla, Niranjan Reddy, Nilsen, Christopher & Andersson, H. I. 2015 On rotational dynamics of inertial disks in creeping shear ow. Physics Letters A, 379, 157-162. http://dx.doi.org/10.1016/j.physleta.2014.10.045 The article in is reprinted with kind permission from Elsevier, sciencedirect.com
Article 2. Challabotla, Niranjan Reddy, Zhao, Lihao & Andersson, H. I. 2015 Orientation and rotation of inertial disk particles in wall turbulence. Journal of Fluid Mechanics, 776, R2. - Is not included due to copyright available at https://doi.org/10.1017/jfm.2015.38
Article 3. Challabotla, Niranjan Reddy, Zhao, Lihao & Andersson, H. I. 2015 Shape e ects on dynamics of inertia-free spheroids in wall turbulence. Physics of Fluids, 27, 61703. http://dx.doi.org/10.1063/1.4922864 © 2015 AIP Publishing LLC. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.
Article 4. Zhao, Lihao, Challabotla, Niranjan Reddy, Variano, Evan A. & Andersson, H. I. 2015 Rotation of nonspherical particles in turbulent channel ow. Physical Review Letters, 115, 244501. https://doi.org/10.1103/PhysRevLett.115.244501 © 2015 American Physical Society
Article 5. Challabotla, Niranjan Reddy, Zhao, Lihao & Andersson, H. I. 2016 Gravity e ects on ber dynamics in wall turbulence. Flow, Turbulence and Combustion, - Is not included due to copyright available at doi:10.1007/s10494-016-9742-5, 2016.
Article 6. Challabotla, Niranjan Reddy, Zhao, Lihao & Andersson, H. I. 2016 On ber behavior in turbulent vertical channel ow. Chemical Engineering Science, 153, 75-86. http://dx.doi.org/10.1016/j.ces.2016.07.002 The article in is reprinted with kind permission from Elsevier, sciencedirect.com
Article 7. Challabotla, Niranjan Reddy, Zhao, Lihao & Andersson, H. I. Orientation and rotation dynamics of tracer triaxial ellipsoidal particles in wall turbulence. - The following article has been accepted and published in Physics of fluids 2016 ;Volum 28.(12) http://dx.doi.org/10.1063/1.4971318 © 2015 AIP Publishing LLC.