JONSWAP Combined Wave And Current Velocity

Calculate JONSWAP combined seabed wave and current velocity from the significant wave height and peak wave period using the JONSWAP spectral moments.

The significant wave velocity and zero upcrossing period are calculated from the JONSWAP spectral moments using a first order Airy wave spectral transformation function. Current velocity can be calculated using either the logarithmic profile, or the one seventh power law profile.

Tool Input

• roughtype : Seabed Roughness Type
  • zou : User Defined Seabed Roughness
• uctype : Current Velocity Type
• gatype : Gamma Factor Type
  • γu : User Defined Gamma
• Vr : Reference Current Velocity
• Zr : Reference Height Above Seabed
• d : Water Depth
• Hs : Wave Significant Height
• Tp : Peak Wave Period
• z : Height Above Seabed

Tool Output

• γ : Gamma Peak Enhancement Factor
• ωp : Wave Peak Frequency
• L : Wave Length
• M0 : 0th Spectral Moment
• M2 : 2nd Spectral Moment
• Tz : Zero Upcrossing Period
• Uc : Current Velocity
• Us : Significant Wave Velocity
• Ut : Wave And Current Combined Velocity
• cvg : Convergence Factor
• kw : Wave Number
• ro : Seabed Roughness

Calculate JONSWAP combined wave and current seabed velocity from return period data using the Weibull, Gumbel or Frechet distributions.

The current velocity is calculated at the design elevation for either the logarithmic profile or the 1/7th power law profile. The logarithmic profile and the power profile are only valid in the boundary layer near the seabed. At elevations well above the seabed measured velocity data should be used. The seabed significant wave induced velocity and zero crossing period are calculated from significant wave height and peak wave period using the JONSWAP surface spectrum with an Airy wave transformation. The calculation is optimised for seabed conditions and should not be used for elevations greater than half the water depth.

Enter data values as sets of four values separated by a comma or tab (R, H, T, Ur), with each data set on a new line. The regression output is tabled at the bottom of the page.

Tool Input

• spwtype : Wave Sample Period Type
  • Swu : User Defined Wave Sample Period
• spctype : Current Sample Period Type
  • Scu : User Defined Current Sample Period
• offtype : Probability Function Parameter Type
  • Hou : User Defined Minimum Wave Height
  • Tou : User Defined Minimum Wave Period
  • Uou : User Defined Minimum Current Velocity
• rtype : Linear Regression Type
• roughtype : Seabed Roughness Type
  • zou : User Defined Seabed Roughness
• uctype : Current Velocity Type
• gatype : Gamma Factor Type
  • γu : User Defined Gamma
• Rdata : Return Period Data
• Hdata : Wave Significant Height Data
• Tdata : Wave Peak Period Data
• Udata : Current Velocity Data
• R : Design Return Period
• d : Water Depth
• Z : Design Elevation Above Seabed
• Zr : Reference Elevation Above Seabed

Tool Output

• γ : Gamma Peak Enhancement Factor
• ωp : Wave Peak Frequency
• Ho : Minimum Wave Height
• Hs : Significant Wave Height
• Hsm : Mean Significant Wave Height
• L : Wave Length
• M0 : 0th Spectral Moment
• M2 : 2nd Spectral Moment
• Sc : Current Sample Period
• Sw : Wave Sample Period
• To : Minimum Wave Period
• Tp : Peak Wave Period
• Tpm : Mean Wave Period
• Tz : Zero Upcrossing Period At Design Elevation
• Uc : Current Velocity At Design Elevation
• Uc/Ut : Current Velocity Over Total Velocity Ratio
• Ur : Current Velocity At Reference Elevation
• Urm : Mean Current Velocity At Reference Elevation
• Us : Significant Wave Velocity At Design Elevation
• Ut : Total Wave And Current Velocity At Design Elevation
• cvg : Convergence Factor
• kw : Wave Number
• ro : Seabed Roughness
• uo : Minimum Current Velocity At Reference Elevation