Chunning Ji
Prof. in Computational Fluid Dynamics
Sediment Transport
The size of the computational box is 6d×d×4d in x, y and z directions, where d is the overall channel depth. The water-worked rough bed consists of two to three layers of densely packed spheres with a diameter of D=0.1d and the height of the roughness elements from the channel bed to the highest crests of the spheres is k=0.3d.
Visualization of instantaneous normalized streamwise fluid velocity fluctuations in three wall-parallel slices located at Y+=0.0 (S4), 21.6 (S3) and 43.3 (S2) (from bottom to top), respectively. The intersection of the particles and the slices are represented by the small white areas which are preferentially distributed in the low-speed fluid region at S4 but scatter at S2 and S3. The well-known quasi-streamwise-aligned streaky structures cease to exist in the near-wall region.
Instantaneous streamwise fluid velocity in a cross-section plane. White areas represent the intersection of the particles with the planes.
The size of the computational box is 6d×d×4d in x, y and z directions, where d is the overall channel depth. The water-worked rough bed consists of two to three layers of densely packed spheres with a diameter of D=0.1d and the height of the roughness elements from the channel bed to the highest crests of the spheres is k=0.3d.
Visualization of the streaky structures in a particle-laden flow.
It is shown that the presence of entrained particles significantly modifies the flow profiles of velocity, turbulent intensities, and shear stresses in the vicinity of a rough bed. The quasi-streamwise-aligned streaky structures are not observed in the near-wall region and the particles scatter on the rough bed owing to their large size. However, in the outer flow region, the turbulent coherent structures recover due to the weakening rough-bed effects and particle interferences. More details refer to my PRE paper, PHYSICAL REVIEW E, 89, 052202 (2014).
Evolution of a sand ripple.
The evolution of a sand ripple simulated by using Large Eddy Simulation, Discrete Particle Method and the Immersed Boundary Method.
The size of the computational box is 10.67d×d×1.33d in x, y and z directions, where d is the overall channel depth. The mobile rough-bed consists of 524K spherical particles with a diameter of d/48. The shields number is 0.235 and the particle Reynolds number is 9.45.
Computational Biofluids
The unique shape of the whiskers of harbor seals leads to the complex three-dimensional vortex structures in their wake.
The unique shape of the whiskers of harbor seals leads to the complex three-dimensional vortex structures in their wake.
The unique shape of the whiskers of harbor seals leads to the complex three-dimensional vortex structures in their wake.
Vortex structures of a Harbor seal whisker model
Harbor seals rely on their wavy whiskers to sense eddy currents in the flow field of their prey's wake and follow them. It is of great scientific significance and application value to study the mechanism of sensing eddy current characteristic of harbour seal whisker. The figures show the three-dimensional vortex structures in the wake of a harbor seal whisker model. More results refer to Journal of Fluid Mechanics. 969, A22 (2023) and Fluids, 8, 206 (2023).