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  2. Limiting amplitude principle - Wikipedia

    en.wikipedia.org/wiki/Limiting_amplitude_principle

    The choice is made by considering a particular time-dependent problem of the forced oscillations due to the action of a periodic force. The principle was introduced by Andrey Nikolayevich Tikhonov and Alexander Andreevich Samarskii. [1] It is closely related to the limiting absorption principle (1905) and the Sommerfeld radiation condition (1912).

  3. Rule of twelfths - Wikipedia

    en.wikipedia.org/wiki/Rule_of_twelfths

    Graph showing relationships between the rule of twelfths (coloured bars), a sine wave (dashed blue curve) and a clockface, if high tide occurs at 12:00. The rule of twelfths is an approximation to a sine curve. It can be used as a rule of thumb for estimating a changing quantity where both the quantity and the steps are easily divisible by 12 ...

  4. Courant–Friedrichs–Lewy condition - Wikipedia

    en.wikipedia.org/wiki/Courant–Friedrichs–Lewy...

    The principle behind the condition is that, for example, if a wave is moving across a discrete spatial grid and we want to compute its amplitude at discrete time steps of equal duration, [2] then this duration must be less than the time for the wave to travel to adjacent grid points. As a corollary, when the grid point separation is reduced ...

  5. Stokes drift - Wikipedia

    en.wikipedia.org/wiki/Stokes_drift

    The Stokes drift is the difference in end positions, after a predefined amount of time (usually one wave period), as derived from a description in the Lagrangian and Eulerian coordinates. The end position in the Lagrangian description is obtained by following a specific fluid parcel during the time interval.

  6. Stokes problem - Wikipedia

    en.wikipedia.org/wiki/Stokes_problem

    The disturbance created by the oscillating plate travels as the transverse wave through the fluid, but it is highly damped by the exponential factor. The depth of penetration δ = 2 ν / ω {\displaystyle \delta ={\sqrt {2\nu /\omega }}} of this wave decreases with the frequency of the oscillation, but increases with the kinematic viscosity of ...

  7. List of equations in wave theory - Wikipedia

    en.wikipedia.org/wiki/List_of_equations_in_wave...

    Position of a point in space, not necessarily a point on the wave profile or any line of propagation d, r: m [L] Wave profile displacement Along propagation direction, distance travelled (path length) by one wave from the source point r 0 to any point in space d (for longitudinal or transverse waves) L, d, r

  8. Stationary phase approximation - Wikipedia

    en.wikipedia.org/wiki/Stationary_phase_approximation

    The second statement is that when f is a Morse function, so that the singular points of f are non-degenerate and isolated, then the question can be reduced to the case n = 1. In fact, then, a choice of g can be made to split the integral into cases with just one critical point P in each.

  9. Critical frequency - Wikipedia

    en.wikipedia.org/wiki/Critical_frequency

    Critical Frequency changes with time of day, atmospheric conditions and angle of fire of the radio waves by antenna. The existence of the critical frequency is the result of electron limitation, i.e., the inadequacy of the existing number of free electrons to support reflection at higher frequencies.