This applet calculates angular wave frequency, wavenumber, and near-bottom horizontal orbital velocity for monochromatic linear gravity waves (c.f. Komar, 1976). The wavenumber k = 2 pi/L, where L is wavelength, is determined from the dispersion equation. Because k is implicit in the dispersion equation, this is normally an iterative calculation with asymptotic solutions for shallow and deepwater cases. This applet uses the explicit approximation suggested by Hunt (1979), which (according to my limited tests) is accurate to within about 0.2%.
This applet calculates particle settling velocities according to three standard equations: the Stokes settling equation (e.g., Neilsen 1992, p.165), the Gibbs equation (also in Neilsen, 1992, p. 165), and the empirical equation developed by Dietrich (1982), which incorporates values of the Powers roundness factor and the Corey shape factor. It also calculates critical shear stress for non-cohesive well-sorted particles using a non-dimensional Sheilds curve ( White, 1970; Gelfenbaum and Smith, 1986. Water properties must be specified in order to calculate water density and viscosity...these routines are the same as the ones in the water properties applet.
This program calculates equilibrium height, wavelength, and steepness of wave-formed ripples on a sandy bottom using the empirical formulations of Wiberg and Harris (1994). Required input is wave height, wave period, water depth, and sand grain diameter. Linear-wave calculations are used to calculate near-bottom orbital velocity and orbital diameter. The ripple geometries are valid only for sand-sized sediments (-1 to 4 phi; 2 to 0.0625 mm), and only when the critical shear stress has been exceeded, but the material is not in suspension. At this point the program does not check the transport criteria carefully...it only suggests that there may be no transport when orbital velocity is less than 0.13 cm/s.
This applet calculates properties of a neutrally stratified wave-current bottom boundary layer using the approach of Madsen (1994). In the absence of waves, the current profile near the bottom is generally logarithmic, taking the form:
u = u*c/kappa * ln( z/zo )
where u is speed at elevation z, u*c is current shear velocity, kappa is von Karmans constant (0.41) and zo is the bottom roughness length. The effect of wave-induced turbulence (which is confined to a thin sublayer within the current boundary layer) is to increase coupling between the currents and the bottom. Assuming that the current velocity at some reference elevation (usually 1 m above the bed) is held constant, the effect of adding waves is to increase drag, as evidenced by a larger "apparent" zoa (or, equivalently, an enhanced bottom-drag coefficient Cde. The shear in the current boundary layer is increased (higher u*c). In addition, the calculations estimate the friction velocity associated with the wave motion (u*w) and the maximum friction velocity of the combined waves and currents u*wc. The calculations presented here assume constant linear eddy viscosities in the current and wave boundary layers, connected by a region of uniform eddy viscosity. A critical assumption is that a single length scale exists, and the solution is formally restricted to the range of roughness indicated in Madsen's Eqn. 32 and 33. Watch for error messages at the bottom of the output.
This applet implements Eqns. 3-39 and 3-40 from the Shore Protection Manual. Input is the 10-m wind speed u [m s-1], the fetch f [km], and the water depth h [m]. The applet adjusts wind speed to adjusted wind speed Ua according to Eqn. 3-28a before being used. The calculations assume a flat bottom with depth h. No checks are made to ensure that reasonable values are entered or that the calculations are within the applicable range.
printfor similar, I will use that.
log10functions, so I pulled out my CRC Math Handbook and kludged some together. I am sure that approach will come back to haunt me later. Watch this space.
The applets in the sedx package have not been completely tested and are not warranted in any way. Please do not use them for any application that involves money, or the welfare of people, animals, or sediment particles.
Development of the sedx package was supported by the Division of Marine Research, Commonwealth Scientific and Research Organisation (CSIRO) in Hobart, Australia. Maintainence is now supported by the USGS, but any errors are the sole responsibility of Chris Sherwood.
If you find errors, please sent email to email@example.com