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Helicity is a pseudo-scalar quantity: it changes sign under change from a right-handed to a left-handed frame of reference; it can be considered as a measure of the handedness (or chirality) of the flow. Helicity is one of the four known integral invariants of the Euler equations; the other three are energy, momentum and angular momentum.
A water model is defined by its geometry, together with other parameters such as the atomic charges and Lennard-Jones parameters. In computational chemistry, a water model is used to simulate and thermodynamically calculate water clusters, liquid water, and aqueous solutions with explicit solvent, often using molecular dynamics or Monte Carlo methods.
In statistical mechanics, the Zimm–Bragg model is a helix-coil transition model that describes helix-coil transitions of macromolecules, usually polymer chains. Most models provide a reasonable approximation of the fractional helicity of a given polypeptide; the Zimm–Bragg model differs by incorporating the ease of propagation (self-replication) with respect to nucleation.
The turbulent Schmidt number is commonly used in turbulence research and is defined as: [3] = where: is the eddy viscosity in units of (m 2 /s); is the eddy diffusivity (m 2 /s).; The turbulent Schmidt number describes the ratio between the rates of turbulent transport of momentum and the turbulent transport of mass (or any passive scalar).
The Standard Model exhibits a (−1) F symmetry, where F is the fermion number operator counting how many fermions are in a state. Since all particles in the Standard Model satisfy F = B + L , the discrete symmetry is also part of the e iα ( B + L ) continuous symmetry group.
Water molecules carry unique isotopic "fingerprints", based in part on differing ratios of the oxygen and hydrogen isotopes that constitute the water molecule. Isotopes are atoms of the same element that have a different number of neutrons in their nuclei. Air, freshwater and seawater contain mostly oxygen-16 ( 16 O).
A typical model of this kind uses a fixed number of sites (often three for water), on each site is placed a parametrized point charge and repulsion and dispersion parameter. These models are commonly geometrically constrained with aspects of the geometry fixed such as the bond length or angles. [14]
In the water cycle, the two main processes that fractionate hydrogen isotopes from seawater are evaporation and condensation. Oxygen isotopic composition (18 O/ 16 O) of water is also an important tracer in the water cycle, and cannot be separated from hydrogen isotopes when we talk about isotope fractionation processes associated with water.