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Chapman–Enskog theory provides a framework in which equations of hydrodynamics for a gas can be derived from the Boltzmann equation. The technique justifies the otherwise phenomenological constitutive relations appearing in hydrodynamical descriptions such as the Navier–Stokes equations .
The fusion of Chapman's and Enskog's theories later became known as the Chapman–Enskog method for solving the Boltzmann equation. In a 1939 book called The Mathematical Theory of Non-Uniform Gases, written by Chapman and Thomas Cowling and dedicated to David Enskog, the authors expanded this theory under the Chapman-Enskog designation.
Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
For instance, the particles are assumed to be pointlike, i.e. without having a finite size. There exists a generalization of the Boltzmann equation that is called the Enskog equation. [22] The collision term is modified in Enskog equations such that particles have a finite size, for example they can be modelled as spheres having a fixed radius.
The kinetic theory of gases allows accurate calculation of the temperature-variation of gaseous viscosity. The theoretical basis of the kinetic theory is given by the Boltzmann equation and Chapman–Enskog theory, which allow accurate statistical modeling of molecular trajectories.
The latter is of significant importance to accurate descriptions of more advanced intermolecular potentials based on perturbation theory, such as SAFT, where a system of hard spheres is taken as a reference system, and the complete pair-potential is described by perturbations to the underlying hard-sphere system.
Plant ecophysiology is concerned largely with two topics: mechanisms (how plants sense and respond to environmental change) and scaling or integration (how the responses to highly variable conditions—for example, gradients from full sunlight to 95% shade within tree canopies—are coordinated with one another), and how their collective effect on plant growth and gas exchange can be ...
The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies greatly, depending on the size of the organism, the environment in which it lives and its evolutionary ...