## Abstract

Drag and lift forces acting on a spherical water droplet in a homogeneous linear shear air flow were studied by means of a three-dimensional direct numerical simulation based on a marker and cell (MAC) method. The effects of the fluid shear rate and the particle (droplet) Reynolds number on drag and lift forces acting on a spherical droplet were compared with those on a rigid sphere. The results show that the drag coefficient on a spherical droplet in a linear shear flow increases with increasing the fluid shear rate. The difference in the drag coefficient between a spherical droplet and a rigid sphere in a linear shear flow never exceeds 4%. The lift force acting on a spherical droplet changes its sign from a positive to a negative value at a particle Reynolds number of Re_{p} ≃ 50 in a linear shear flow and it acts from the high-speed side to the low-speed side for Re_{p} ≥ 50. The behaviour of the lift coefficient on a spherical droplet is similar to that on a stationary rigid sphere and the change of sign is caused by the decrease of the pressure lift. The viscous lift on a spherical droplet is smaller than that on a rigid sphere at the same Re_{p}, whereas the pressure lift becomes larger. These quantitative differences are caused by the flow inside a spherical droplet.

Original language | English |
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Pages (from-to) | 155-175 |

Number of pages | 21 |

Journal | Journal of Fluid Mechanics |

Volume | 570 |

DOIs | |

Publication status | Published - 2007 Jan 10 |

Externally published | Yes |

## ASJC Scopus subject areas

- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering