Time Required to Lower Liquid Surface using Bazins Formula Calculator

Bazins Formula:

\[ \Delta t = \frac{2 \times A_R}{m \times \sqrt{2 \times g}} \times \left( \frac{1}{\sqrt{h_2}} - \frac{1}{\sqrt{H_{\text{Upstream}}}} \right) \]

Cross-Sectional Area of Reservoir (A_R):

m²

Bazins Coefficient (m):

Acceleration due to Gravity (g):

m/s²

Head on Downstream of Weir (h₂):

Head on Upstream of Weir (H_Upstream):

Time Interval (Δt):

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1. What is Bazins Formula?

Bazins Formula is used to calculate the time required to lower the liquid surface in a reservoir through a weir. It considers the cross-sectional area of the reservoir, Bazins coefficient, acceleration due to gravity, and the heads on both upstream and downstream sides of the weir.

2. How Does the Calculator Work?

The calculator uses Bazins Formula:

\[ \Delta t = \frac{2 \times A_R}{m \times \sqrt{2 \times g}} \times \left( \frac{1}{\sqrt{h_2}} - \frac{1}{\sqrt{H_{\text{Upstream}}}} \right) \]

Where:

\( \Delta t \) — Time Interval (s)
\( A_R \) — Cross-Sectional Area of Reservoir (m²)
\( m \) — Bazins Coefficient
\( g \) — Acceleration due to Gravity (m/s²)
\( h_2 \) — Head on Downstream of Weir (m)
\( H_{\text{Upstream}} \) — Head on Upstream of Weir (m)

Explanation: The formula calculates the time required for the liquid surface to lower from the upstream head to the downstream head, accounting for the reservoir's geometry and flow characteristics through the weir.

3. Importance of Time Interval Calculation

Details: Accurate calculation of time interval is crucial for reservoir management, flood control, irrigation scheduling, and hydraulic structure design. It helps in predicting how quickly water levels will change in response to weir operations.

4. Using the Calculator

Tips: Enter all values in appropriate units. Cross-sectional area should be in square meters, heads in meters, acceleration due to gravity in m/s² (typically 9.8 m/s²). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is Bazins Coefficient?
A: Bazins Coefficient is an empirical constant that accounts for the discharge characteristics of the weir. It varies depending on the weir geometry and flow conditions.

Q2: When is this formula applicable?
A: This formula is applicable for calculating the time required to lower liquid surface in reservoirs with weirs, particularly for sharp-crested weirs under specific flow conditions.

Q3: What are typical values for Bazins Coefficient?
A: Bazins Coefficient typically ranges from 0.4 to 0.6 for sharp-crested weirs, but the exact value depends on the specific weir configuration and should be determined experimentally.

Q4: Are there limitations to this formula?
A: Yes, the formula assumes ideal flow conditions and may need adjustments for very large or very small heads, complex reservoir shapes, or non-standard weir configurations.

Q5: How accurate is this calculation?
A: The accuracy depends on the precision of input values and how well the actual conditions match the assumptions of Bazins formula. For critical applications, experimental verification is recommended.