The hydrodynamics is a very important area of study in the field of physics that when materials are compressed explosively are exposed to a series of conditions extreme that make them behave more like a liquid . The literal meaning of hydrodynamics is ” movement of water “ . In itself we can say that it is the science of forces acting on fluids.


What is hydrodynamics?

Hydrodynamics is the science that is responsible for studying fluids in motion , which is defined by means of a vertical field of speeds that correspond to the particles of a fluid and the pressures in a scalar field.

  • Definition of hydrodynamics
  • What studies
  • History
  • Hydrodynamic applications
  • features
  • Concepts
  • Laws of hydrodynamics
  • Formula
  • Experiment
  • Importance of hydrodynamics
  • Examples
  • Books

Definition of hydrodynamics

Hydrodynamics is the part of hydraulics and physics that is responsible for studying the way in which different liquids that are in motion behave . To achieve this purpose, hydrodynamics considered among other things a number of aspects such as speed , the pressure , the flow and spending of the liquid.


It is important to mention that in order to study hydrodynamics, it is important to know Bernoulli’s theorem , a treatise that tells us about the law of conservation of energy . This is because the theorem tells us that the sum of the kinetic , potential and pressure energies that we can find in a liquid that is in motion at a certain point is equal to that of any other point.

What studies

Hydrodynamics is a science that is responsible for studying and investigating mainly incompressible fluids , this means, that it is responsible for studying liquids, because their density practically does not vary when changes are made in the pressure that is exerted. about them. We can say that it is the science that allows us to understand how different liquids can interact with the environment and also with each other.


Basically the history of hydrodynamics begins in Mesopotamia and Egypt , around 400 BC As history progressed, a series of inventions were made that helped develop what we know today as fluid dynamics . By the end of the 19th century, he began to unite the concepts of hydraulics and hydrodynamics .

The history of hydrodynamics begins with Archimedes’ principle , which tells us that every body that is submerged in a fluid experiences a vertical upward thrust that is equal to the weight of the fluid that has been dislodged . This principle tells us the relationship that exists between the buoyancy force that a body has and the fluid that this same liquid is capable of displacing.

It is also important to remember that fluid dynamics , an important part of the history of hydrodynamics, was the Swiss physicist Daniel Bernoulli, who after working with fluids, managed to discover the relationship between their forces .

Hydrodynamic applications

The applications of hydrodynamics are many, among them we mention the following:

  • Construction of canals and aqueducts
    • To know the amount of water to be dislodged, at what speed and in how long.
  • Plumbing
    • In creating simple plumbing to avoid unnecessary water waste.
  • Rain collectors
    • To make the streets able to evacuate the water in the cities to avoid floods.
  • Aviation
    • Helping planes take off.
  • Boat manufacturing
  • Automobiles
    • Creation of more aerodynamic cars and in fuel economy .
    • Hydraulic jacks.
    • Cranes
    • Dampers.


The main characteristics of hydrodynamics are represented by means of mathematical equations and are the following:

  • Torricelli’s law, which is the law that tells us that if there is a fluid in a container that is not covered and a hole is opened in the container, the speed with which that fluid will fall will be: V = √ (2gh)
  • The Reynolds motion that describes the fluids that are in motion by means of the following formula: N = (p · D · v) / n , in which p is the density, D the diameter of the cylinder, v the velocity and n the viscosity.
  • The flow rate which is the volume of the liquid that flows in a unit of time. Its formula is: G = ΔV / Δt
  • The Bernoulli principle which is a consequence of the conservation of energy in liquids that are in motion.


  • Fluids : it is a continuous medium formed by a substance between whose molecules there is a weak attractive force and are characterized in that they can change shape without there being restitutive forces tending to recover the “original” shape.
  • Surface tension : it is the amount of energy that is needed to increase its surface per unit area.
  • Flow : is the amount of fluid that passes in a unit of time .
  • Fluid mechanics is the part of the mechanics of continuous media and the branch of physics that deals with the motion of the fluid and the forces that cause them .
  • Turbulent flow : it is the movement of a fluid in a chaotic way in which the particles move disorderly and the trajectories form aperiodic eddies .
  • Laminar flow : it is the movement of a fluid when it is ordered , stratified , smooth .

Laws of hydrodynamics

The main laws of the motion of fluids and of the magnitudes are made by means of mathematical laws that are:

  • Equation of continuity : it is an equation that tells us about the conservation of mass and its formula is 1 ∙ S 1 = v 2 ∙ S 2
  • Bernoulli’s principle : establishes that an ideal fluid that is in circulation through a closed conduit will always have a constant energy during its travel.
  • Torricelli’s Law: it is an adaptation of Bernoulli’s principle and studies the way in which a liquid behaves when it is inside a container when it moves through a small hole by the force of gravity .


The mathematical expression that is used as the fundamental principle of Hydrodynamics, or Bernoulli’s principle , is the following:

1 + ρ. g. h 1 + ½. ρ. v 1 ² = P 1 + ρ. g. h 2 + ½. ρ. v 2 ²


  • P: hydrostatic pressure ;
  • p: the density;
  • g: the acceleration of gravity;
  • h: the height of the point;
  • v: the velocity of the fluid at that point.


An example of an easy experiment to perform that hydrodynamics teaches us is:

  • Two plastic syringes are taken , one larger than the other, they are connected by means of a plastic hose , through which the liquid for injections comes out, a syringe is filled with water and it must be left empty . When you put pressure on the plunger of the syringe that is filled with liquid you can see that less force is needed to make the “other injector” move, and this is the way hydraulic mechanical presses work, with the same principle

Importance of hydrodynamics

Hydrodynamics is a very important area for daily life because it is responsible for the study of liquids , mainly water , which is the vital liquid for our lives. Through it, different studies can be carried out and applications created to be able to make the distribution of this precious liquid possible.


Some examples where we can observe hydrodynamics are:

  • Sailboat Sailing
  • Hydraulic Turbine
  • Water Circulation Through Pipes
  • Water skiing
  • Hydraulic jacks
  • Transport cranes
  • Dampers
  • Brakes


Among the most recognized literature that has been developed to explain hydrodynamics we can mention the following:

  • Introduction to Classical Hydrodynamics: Rosa Maria Velasco.
  • Environmental Hydrodynamics of Dr. Marcelo García.
  • The birth of The Birt Theoretical Hydrodynamics.

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