Biofluid dynamics may be considered as the discipline of biological engineering or biomedical engineering in which the fundamental principles of fluid dynamics are used to explain the mechanisms of biological flows and their interrelationships with physiological processes, in health and in diseases/disorder. It can be considered as the conjuncture of mechanical engineering and biological engineering. It spans from cells to organs, covering diverse aspects of the functionality of systemic physiology, including cardiovascular, respiratory, reproductive, urinary, musculoskeletal and neurological systems etc. Biofluid dynamics and its simulations in computational fluid dynamics (CFD) apply to both internal as well as external flows. Internal flows such as cardiovascular blood flow and respiratory airflow, and external flows such as flying and aquatic locomotion (i.e., swimming). Biological fluid Dynamics (or Biofluid Dynamics) involves the study of the motion of biological fluids (e.g. blood flow in arteries, animal flight, fish swimming, etc.). It can be either circulatory system or respiratory systems. Understanding the circulatory system is one of the major areas of research. The respiratory system is very closely linked to the circulatory system and is very complex to study and understand. The study of Biofluid Dynamics is also directed towards finding solutions to some of the human body related diseases and disorders. The usefulness of the subject can also be understood by seeing the use of Biofluid Dynamics in the areas of physiology in order to explain how living things work and about their motions, in developing an understanding of the origins and development of various diseases related to human body and diagnosing them, in finding the cure for the diseases related to cardiovascular and pulmonary systems.
History of Bio Fluid Dynamics
The History of Bio-Fluid Dynamics may be considered very old dating back to 2700-2600 BC when for the first time a written document on circulation of blood and theories of Chinese medicine called "Internal Classics" was written by the Chinese emperor Huang ti also called as the yellow emperor. The Most notable names related to the field of biofluid Dynamics are of William Harvey, Jean Louis Marie Poiseuille, and Otto Frank. In 1628, Harvey published, "An anatomical study of the motion of the heart and of the blood of animals." This was the first publication in the Western World that claimed that blood is pumped from the heart and recirculated. Jean Louis Marie Poiseuille is credited with developing the theory of Poiseuille's Flow. It describes the relationship between flow and pressure gradient in long tubes with constant cross section. Otto Frank published the "Fundamental form of the arterial pulse," which contained his "Windkessel theory" of circulation in 1890. He also perfected optical manometers and capsules for the precise measurement of intra-cardiac pressures and volumes. Huge research efforts focus these days to understand intrinsic biofluid dynamics to shed light on mechanisms in physiology and pathophysiology. This list contains details of some of the major research groups focusing efforts in this area.
Basic Principles of Fluid Dynamics
A fluid is defined as a substance that deforms continuously under application of a shearing stress, regardless of how small the stress is. Blood is a primary example of a biological fluid. Air can also be considered as biological fluid as it flows in lungs and the synovial fluid between the knee joints is also an example of a biological fluid. Types of Fluids Fluids can be classified into four basic types. They are:
Ideal Fluid
Real Fluid
Newtonian Fluid
Non-Newtonian fluid
An Ideal Fluid is a fluid that has no viscosity, means it will offer no resistance, pragmatically this type of fluid does not exist. It is incompressible in nature. Real fluids are compressible in nature. They offer some resistance and thus have viscosity. All Fluids existing are real fluids. A Newtonian Fluid is a fluid whose viscous shear stresses (acting between different layers of fluid and between the fluid layer and surface over which it is flowing) are directly proportional to the rate of change of velocity of the flow of the fluid with respect to the distance in the transverse direction (distance measured perpendicular to the flow), also known as velocity gradient. The constant of proportionality is known as the dynamic viscosity of the fluid denoted by 'μ'. The functional relationship between viscous shear stress and velocity gradient is linear in a Newtonian fluid. This relationship may be written as :