2-Dimension freely falling plates with different mass distributions are simulated by numerically solving the equations of motion coupling with the Navier-Stokes equations. With moving mesh
the motions related to different parameters are studied. The trajectories are identified and the unsteady dynamics are given by considering different dimensionless moments of inertia
and the initial falling angle and centroid positions. The results show that
except the three known classical trajectories:fluttering
tumbling
steady descent
we also observe two new motions. These motions are asymmetrical-fluttering and flutter-tumbling trajectories. They are caused by the centroid position deviating from the center of the plate and the dimensionless moment o
f inertia in the range of 0~0.95. These motions turn to the tumbling when the centroid position is beyond 0.13
L
. It indicates that the dimensionless moment of inertia and centroid position are important parameters in freely falling plates
but the physical mechanisms are different in falling motions. The present results can provide academic reference in study of low Reynolds number problems.
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references
BELMONTE A, EISENBERG H, MOSES E. From flutter to tumble:inertial drag and froude similarity in falling paper[J]. Physical Review Letters, 1998, 81(2):345-348.
ANDERSEN A, PESAVENTO U, WANG Z J. Unsteady aerodynamics of fluttering and tumbling plates[J]. J Fluid Mech, 2005, 541:65-90.
PESAVENTO U, WANG Z J. Falling paper:Navier-Stokes solutions, model of fluid forces, and center of mass elevation[J]. Physical Review Letters, 2004, 93(14):4501.
WAN H, DONG H, LIANG Z. Vortex formation of freely falling plates[R]. AIAA 2012-1079, 2012.
TIAN R, SHU F. Experimental study of the fluid and structure interaction for gravity driven falling plates[C]//Aps Division of Fluid Dynamics Meeting, 2014.
TIAN R. Experimental and theoretical study of fluid-structure interactions in plunging hydrofoils and gravity-driven falling plates[D]. New Mexico State University, 2015: 77-85.
KUBOTAL Y, MOCHIZUKI O. Numerical investigation of aerodynamic characteristics by a rotating thin plate[J]. World Journal of Mechanics, 2015, (5):42-47.
HU R, WANG L. Motion transitions of falling plates via quasi-steady aerodynamics[J]. Physical Review E, 2014, 90:013020.
ZHONG H J, LEE C B. The wake of falling disks at low Reynolds numbers[J]. Acta Mech Sin, 2012, 28(2):367-371.
ZHONG H J, YCHEN S, LEEC B. Experimental study of freely falling thin disks:transition from planar zigzag to spiral[J]. Physics of Fluids, 2011, 23(1):011702.
ZHOU Q. The study of unsteady aerodynamics of freely falling plates[D]. Shanghai Jiao Tong University, 2012.
SUN M. Aerodynamics of animal flight[J]. Acta Aerodynamica Sinica, 2018, 36(1):122-128. (in Chinese)
SUN M, TANG J. Unsteady aerodynamic force generation by a model fruit fly wing in flapping motion[J]. The Journal of Experimental Biology, 2002, 205:55-70.
ROGERS S E, KWAK D. Upwind differencing scheme for the time-accurate incompressible Navier-Stokes equations[J]. AIAA Journal, 1990, 28(2):253-262.
ROGERS S E, KWAK D, KIRIS C. Numerical solution of the incompressible Navier-Stokes equations for steady-state and time-dependent problems[C]//AIAA 27th Aerospace Sciences Meeting. Washington, D.C: American Institute of Aeronautics and Astronautics, 1989: 89-0463.
LIANG B, SUN M. Nonlinear flight dynamics and stability of hovering model insects[J]. J R Soc Interface, 2013, 10:20130269.