The sound of a waterfall can add a sense of calm to a space. The owner of the pictured waterfall wanted to increase the sound effect by causing the water to develop turbulent flow 0.4 m from the top. i)If the kinematic viscosity of the water in the garden at 20°C is 1.004 x 10$ m²/s , what flow rate would the owner need to use. Show your calculations. ii) What would happen to the point of turbulence in the winter when the temperature dops a few degrees, but flow rate is maintained at the summer value, explain your answer?

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**Understanding Waterfall Sound and Turbulent Flow Creation**

The sound of a waterfall can add a sense of calm to a space. The owner of the pictured waterfall wanted to increase the sound effect by causing the water to develop turbulent flow 0.4 m from the top.

**Part i)** If the kinematic viscosity of the water in the garden at 20°C is \(1.004 \times 10^{-5} \, m^2/s\), what flow rate would the owner need to use? **Show your calculations.**

**Part ii)** What would happen to the point of turbulence in the winter when the temperature drops a few degrees, but the flow rate is maintained at the summer value? Explain your answer.

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**Detailed Explanation:**

In this problem, we aim to find the necessary flow rate to achieve turbulent flow at a specified distance from the top of the waterfall, and then analyze what happens under different temperature conditions.

### Part i) Calculation of Flow Rate for Turbulent Flow

To achieve turbulent flow, we must consider the Reynolds number (Re), defined as:

\[ \text{Re} = \frac{\rho \cdot v \cdot L}{\mu} \]

However, for a waterfall, the flow along a vertical surface, the Reynolds number can be written in terms of kinematic viscosity (\( \nu \)):

\[ \text{Re} = \frac{v \cdot L}{\nu} \]

Where:
- \( \nu \) is the kinematic viscosity.
- \( D \) is the characteristic length (0.4 m in our case).

We assume turbulent flow occurs when Re > 4000. We solve for the flow rate.

Given that \( \nu = 1.004 \times 10^{-5} \, m^2/s \), and \( L = 0.4 \, m \):

\[ \text{Re} = \frac{Q \cdot L}{\nu} \]

where \( v \) is the velocity, which can be obtained from the flow rate \( Q \) (consider cross-sectional area as \( A \)):

\[ v = \frac{Q}{A} \]

Combining the equations:

\[ 4000 = \frac{Q \cdot 0.4}{1.004 \times 10^{-5}} \]

Solving for \( Q \):

\[ Q =
Transcribed Image Text:**Understanding Waterfall Sound and Turbulent Flow Creation** The sound of a waterfall can add a sense of calm to a space. The owner of the pictured waterfall wanted to increase the sound effect by causing the water to develop turbulent flow 0.4 m from the top. **Part i)** If the kinematic viscosity of the water in the garden at 20°C is \(1.004 \times 10^{-5} \, m^2/s\), what flow rate would the owner need to use? **Show your calculations.** **Part ii)** What would happen to the point of turbulence in the winter when the temperature drops a few degrees, but the flow rate is maintained at the summer value? Explain your answer. --- **Detailed Explanation:** In this problem, we aim to find the necessary flow rate to achieve turbulent flow at a specified distance from the top of the waterfall, and then analyze what happens under different temperature conditions. ### Part i) Calculation of Flow Rate for Turbulent Flow To achieve turbulent flow, we must consider the Reynolds number (Re), defined as: \[ \text{Re} = \frac{\rho \cdot v \cdot L}{\mu} \] However, for a waterfall, the flow along a vertical surface, the Reynolds number can be written in terms of kinematic viscosity (\( \nu \)): \[ \text{Re} = \frac{v \cdot L}{\nu} \] Where: - \( \nu \) is the kinematic viscosity. - \( D \) is the characteristic length (0.4 m in our case). We assume turbulent flow occurs when Re > 4000. We solve for the flow rate. Given that \( \nu = 1.004 \times 10^{-5} \, m^2/s \), and \( L = 0.4 \, m \): \[ \text{Re} = \frac{Q \cdot L}{\nu} \] where \( v \) is the velocity, which can be obtained from the flow rate \( Q \) (consider cross-sectional area as \( A \)): \[ v = \frac{Q}{A} \] Combining the equations: \[ 4000 = \frac{Q \cdot 0.4}{1.004 \times 10^{-5}} \] Solving for \( Q \): \[ Q =
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