Total Or Absolute Pressure Calculator

Formula Used:

\[ P_{abs} = \frac{\rho \cdot g \cdot H \cdot \cosh\left(\frac{2\pi(D_z + d)}{\lambda}\right) \cdot \cos(\theta)}{2 \cdot \cosh\left(\frac{2\pi d}{\lambda}\right)} - \rho \cdot g \cdot Z + P_{atm} \]

Mass Density (ρ):

kg/m³

Wave Height (H):

Distance above Bottom (Dz):

Wavelength (λ):

Phase Angle (θ):

rad

Water Depth (d):

Seabed Elevation (Z):

Atmospheric Pressure (P_atm):

Absolute Pressure (P_abs):

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1. What is the Total or Absolute Pressure Equation?

The Total or Absolute Pressure equation calculates the complete pressure at a specific point in a fluid environment, accounting for atmospheric pressure, hydrostatic pressure, and wave-induced pressure variations. It is essential for coastal engineering and marine structure design.

2. How Does the Calculator Work?

The calculator uses the Absolute Pressure equation:

\[ P_{abs} = \frac{\rho \cdot g \cdot H \cdot \cosh\left(\frac{2\pi(D_z + d)}{\lambda}\right) \cdot \cos(\theta)}{2 \cdot \cosh\left(\frac{2\pi d}{\lambda}\right)} - \rho \cdot g \cdot Z + P_{atm} \]

Where:

\( \rho \) — Mass density (kg/m³)
\( g \) — Gravitational acceleration (9.80665 m/s²)
\( H \) — Wave height (m)
\( D_z \) — Distance above bottom (m)
\( \lambda \) — Wavelength (m)
\( \theta \) — Phase angle (rad)
\( d \) — Water depth (m)
\( Z \) — Seabed elevation (m)
\( P_{atm} \) — Atmospheric pressure (Pa)

Explanation: The equation accounts for wave-induced pressure variations, hydrostatic pressure, and atmospheric pressure to determine the total pressure at a specific point in the water column.

3. Importance of Absolute Pressure Calculation

Details: Accurate absolute pressure calculation is crucial for designing marine structures, assessing coastal erosion, and understanding sediment transport processes in coastal environments.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Ensure values are physically meaningful (positive densities, realistic wave parameters, etc.) for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between absolute pressure and gauge pressure?
A: Absolute pressure is measured relative to a perfect vacuum, while gauge pressure is measured relative to atmospheric pressure. Absolute pressure = Gauge pressure + Atmospheric pressure.

Q2: Why is the hyperbolic cosine function used in this equation?
A: The cosh function accurately describes how wave-induced pressure decays with depth, providing a more realistic pressure distribution in the water column.

Q3: How does wave height affect absolute pressure?
A: Higher wave heights generate greater pressure fluctuations, leading to increased loading on marine structures and enhanced sediment mobility.

Q4: What is the significance of phase angle in this calculation?
A: Phase angle determines the timing relationship between wave oscillation and pressure response, affecting the magnitude and timing of pressure variations.

Q5: When is this equation most applicable?
A: This equation is particularly useful for coastal engineering applications, including breakwater design, offshore structure analysis, and coastal sediment transport studies.