Applied fluid dynamics is the technology of the streams or flowing and can also be used as a technique of the movement of fluids and the movement of bodies in fluids in this field.

The forces that move the fluids can act in the whole volume or on the surface. The main parameters of this movement are the velocities and pressures, but also the temperature of the fluids can play a vital role. Fluids can be gases, liquids, plasma or mixtures of gases, liquids and / or solids. All these so-called phases of matter, depending on the situation, can also be considered in fluid mechanics.  Cosmic phenomena can be mentioned as an extreme example since also fluid-mechanical models are used for their theoretical investigations. These are discussed in the context of cosmology. Other complex fluid mechanical processes take place in the atmosphere and those are treated within meteorology. The phenomena associated with plasma are treated in the framework of plasma physics. Also solids can flow, such as glass, glaciers or metals. The flow velocity depends on the temperature and the strain. 

What remains are fluid mechanical phenomena on earth with the remaining three phases gas, liquid and solid as well as the phase transitions between these phases and mixtures. Usually the dimensions of the bodies – in or with fluids - are small compared to the examination area. Areas of technology where fluid technology plays a crucial role are among others mechanical engineering, plant engineering, vehicle and building construction. Several specialistations emerged from those such as engineering, traffic engineering, power engineering, construction engineering, systems engineering, system technology, heating technology, air technology, air conditioning, water technology, measurement technology, ... Listing all areas of technology where flows of fluids occur is beyond the scope of a website. The fluid flow engines, the pipes and channels as well as the gauges alone can be found almost everywhere in today’s technical environment.

The movement of bodies in fluids is the key issue of traffic engineering, which is classified into aviation, marine transport, rail and road. All of these have significant flow-technical aspects which appear both on the outside (driving, floating, buoyancy, resistance etc.) as well as on the inside of vehicles (propulsion, ventilation and air conditioning, heating and cooling etc.).