 Fluid Mechanics is the branch of physics concerned with the mechanics of fluids, liquids, gases, and plasmas and the forces on them. Fluid Mechanics has a wide range of applications, including mechanical engineering, civil engineering, chemical engineering, biomedical engineering, geophysics, astrophysics, and biology. Fluid Mechanics can be divided into fluid statics, the study of fluids at rest, and fluid dynamics, the study of the effect of forces on fluid motion. It is a branch of continuum mechanics, the subject which modeled matter without using the information that it is made out of atoms. That is, it modeled matter from a macroscopic viewpoint rather than from microscopic. Fluid Mechanics, especially fluid dynamics, is an active field of research with many problems that are partly or wholly unsolved. Fluid Mechanics can be mathematically complex, and can best be solved by numerical methods, typically using computers. The modern discipline, called computational fluid dynamics CFE is devoted to this approach to solving fluid mechanics problems. Particle image velocity tree, an experimental method for visualizing and analyzing fluid flow, also takes advantage of the highly visual nature of fluid flow.