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CALCULATOR MODULE : Ocean Current ±
Calculate current velocity versus water depth using either the logarithmic profile or the 1/7th power law profile. The current velocity is calculated relative to a measured reference velocity at a reference elevation. For best results the reference velocity should be measured at an elevation close to the target elevation. Current flow can be stratified with different layers moving at different speeds and directions. The current velocity can be calculated at a single point or averaged over a range. The logarithmic and power law profiles are only valid in the current boundary layer near the seabed. Related Modules : |
CALCULATOR MODULE : Morison's Equation Wave And Current Load ±
Calculate wave and current loads on submerged structures using Morison's equation (Airy Stokes and Cnoidal waves). For vertical structures the load forces are due to the horizontal velocity and acceleration only. For horizontal structures the load forces also include vertical velocity and acceleration. Lateral (lift) forces are due to non symmetric flow around the structure, either because of proximity to the seabed or another structure, or by non symmetric cross section. The Keulegan Carpenter number is a measure of the ratio of wave inertial forces and drag forces. Change Module : |
CALCULATOR MODULE : Morison's Equation Wave Slam ±
Calculate wave slamming loads on submerged structures using Morison's equation (Airy Stokes and Cnoidal waves). Wave slamming loads are due to the impact of the wave surface against the structure. The combined wave loading includes wave drag load, inertia load, and lateral load. For horizontal structures buoyancy load is also included. Wave slamming loads occur on the front of the wave only (phase angle ≤ 180 degrees). Wave loads are calulated at the wave surface (wave surface height is calculated from wave phase angle). theoretical wave slamming load coefficient varies between π and 2 π. The calculated wave slamming load is force per length (unit force). To calculate the total load (force) on a vertical structure the wave curl coefficient can be used `Lt = λ Hw Fs ` where : Lt = the total load (force)
λ = the wave curl coefficient
Hw = the wave height
Fs = the slamming load (force per length) The wave curl coefficient accounts for the variation in time for the wave to contact the whole vertical structure. Typical values of the wave coefficient λ vary from 0.4 to 0.9. Change Module : |
CALCULATOR MODULE : Morison's Equation Drag Lift And Inertia Coefficient ±
Calculate drag coefficient, lift coefficient and inertia coefficient for Morison's equation. Drag, lift, and inertia coefficients are affected by proximity to the seabed or another structure. In open water the lateral coefficient tends to zero. The Keulegan Carpenter number is a measure of the ratio of inertial forces and drag forces. Change Module : |
CALCULATOR MODULE : Morison's Equation Wave And Current Amplitude ±
Calculate wave and current amplitude for Morison's equation from return period data. Wave and current amplitude is calculated from return period data using linear regression with either the Weibull, Gumbel or Frechet probability distributions. Use the Result Plot option to display plots for the selected wave type etc. Details of the linear regression are displayed in the output at the bottom of the page. Change Module : Related Modules : |
CALCULATOR MODULE : Ocean Wave And Current Velocity And Acceleration ±
Calculate ocean wave and current velocity and acceleration for Airy, Stokes, cnoidal and JONSWAP waves. Wave velocity and acceleration can be calculated for Airy, Stokes, and Cnoidal waves. The recommended wave type is displayed below the calc bar. Use the Result Plot option to compare the Airy, Stokes, and cnoidal wave profiles. The seabed significant wave velocity and zero upcrossing period can be calculated from the JONSWAP surface spectrum. Current velocity can be calculated near the seabed using either the logarithmic profile, or the 1/7th power law profile. The logarithmic and power law profiles are not valid For large elevations above the seabed. Note : The Stokes and cnoidal waves use trucated infinite series. Under certain conditions the truncated series do not converge properly. The Stokes wave is not suitable for shallow water waves. The cnoidal wave is not suitable for deep water waves. The recommended wave type is displayed below the calc bar. The JONSWAP wave uses an Airy wave transfer function to calculate seabed velocity. The JONSWAP wave is not suitable for very shallow waves (near breaking). Change Module : |
CALCULATOR MODULE : Ocean Wave And Current Seabed Stability ±
Calculate subsea critical seabed velocity for seabed stability and sediment movement from the critical shields number. The Shields parameter is used to calculate the onset of seabed instability due to sediment movement. For subsea waves and currents the critical Shields parameter is approximately 0.04. For laminar flow the critical Shields parameter is approximately 0.03. Change Module : |
CALCULATOR MODULE : Ocean Wave And Current Self Burial ±
Calculate subsea pipeline self burial due to seabed movement on a sandy seabed. Piping occurs on mobile sandy seabeds, and is not applicable for rock or clay seabeds. Change Module : |
CALCULATOR MODULE : Ocean Wave Directionality And Spreading ±
Calculate ocean wave velocity reduction factor from relative heading and spreading factor. The spreading factor accounts for wave "choppiness" or superimposed multi directional waves. Locally generated waves are generally short crested and more "choppy", and are characterised by small spreading factors. Long range swells are generally long crested uni directional waves, and are characterised by large spreading factors. Change Module : |
CALCULATOR MODULE : Ocean Current Probability And Return Period ±
Calculate ocean current velocity from return period data using the Weibull, Gumbel or Frechet probability distributions. The three parameter distribution and Z offset is used to account for a minimum value, the smallest event which can occur in any sample period. The best fit line is calculated for the data points using the least squares linear regression method. The regression is calculated for return period versus amplitude (the X and Z values are swapped). Use the Data Plot option on the plot bar to display the data points and the calculated best fit. The regression data points and regression parameters are displayed in the output view at the bottom of the page. Change Module : Related Modules : |
CALCULATOR MODULE : Ocean Wave And Current Probability And Return Period ±
Calculate ocean wave height, wave period and current velocity from return period data using the Weibull, Gumbel or Frechet probability distributions. The three parameter distribution and Z offset is used to account for a minimum value, the smallest event which can occur in any sample period. The best fit line is calculated for the data points using the least squares linear regression method. The regression is calculated for return period versus amplitude (the X and Z values are swapped). Use the Data Plot option on the plot bar to display the data points and the calculated best fit. The regression data points and regression parameters are displayed in the output view at the bottom of the page. Change Module : Related Modules : |
CALCULATOR MODULE : JONSWAP Combined Wave And Current Velocity ±
Calculate JONSWAP seabed wave and current amplitude from return period data. Return period data can be analysed using either the Weibull, Gumbel or Frechet distribution. Current velocity can be calculated using either the logarithmic profile, or the 1/7th power law profile. The logarithmic and power law profiles are only valid in the boundary layer on or near the seabed. The seabed velocity and upcrossing period is calculated from the JONSWAP surface spectrum using a first order Airy wave transformation. The calculation may not be valid in shallow water, and is not recommended for elevations greater than half the water depth. Reference : Hasselmann K et al : Measurements of Wind-Wave Growth And Swell Decay During The Joint North Sea Wave Project (JONSWAP) Change Module : |