@inproceedings{c2fd21a0f67745968a3bff7c44336a20,
title = "Control over multiscale mixing in broadband-forced turbulence",
abstract = "The effects of explicit flow modulation on the dispersion of a passive scalar field are studied. Broadband forcing is applied to homogeneous isotropic turbulence to modulate the energy cascading and alter the kinetic energy spectrum. Consequently, a manipulation of turbulent flow can be achieved over an extended range of scales beyond the directly forced ones. This modifies transport processes and influences the physical-space turbulent mixing of a passive scalar field. We investigate by direct numerical simulation the stirring-efficiency associated with turbulence modified by forcing. This is quantified by monitoring the surface-area and wrinkling of a level-set of the passive scalar field. We consider different forcing to manipulate the quality and rate of mixing. The instantaneous mixing efficiency measured in terms of surface-area or wrinkling is found to increase when additional energy is introduced at the smaller scales. The increased intensity of small scales significantly influences the small-scale mixing characteristics depicted by wrinkling, while the forcing of large scales primarily affects the surface-area. Evaluation of geometrical statistics in broadband-forced turbulence indicates that the self-amplification process of vorticity and strain is diminished. This leads generally to smaller extremal values of the velocity gradients but higher average values as a result of the competition between the natural cascading processes and the explicit small-scales forcing.",
keywords = "EWI-14732, IR-65255, METIS-238752",
author = "Kuczaj, \{Arkadiusz K.\} and Geurts, \{Bernardus J.\}",
note = "http://dx.doi.org/10.1007/978-1-4020-6472-2\_20 ; IUTAM symposium on computational physics and new perspectives in turbulence ; Conference date: 11-09-2006 Through 14-09-2006",
year = "2008",
doi = "10.1007/978-1-4020-6472-2\_20",
language = "Undefined",
isbn = "978-1-4020-6472-2",
series = "IUTAM Bookseries",
publisher = "Springer",
number = "11",
pages = "131--136",
booktitle = "IUTAM symposium on computational physics and new perspectives in turbulence",
address = "Germany",
}