1. What is Drag Force in Fluid?

Definition: Drag force is the resistance force exerted by a fluid (liquid or gas) on an object moving through it.

Purpose: This calculator helps engineers, physicists, and designers determine the drag force experienced by objects in fluid flow.

2. How Does the Calculator Work?

The calculator uses the drag force formula:

Where:

• \( F_d \) — Drag force (Newtons, N)
• \( \rho \) — Fluid density (kg/m³)
• \( v \) — Velocity of object relative to fluid (m/s)
• \( C_d \) — Drag coefficient (dimensionless)
• \( A \) — Cross-sectional area (m²)

Explanation: The formula shows drag force is proportional to fluid density, velocity squared, and object's cross-sectional area.

3. Importance of Drag Force Calculation

Details: Understanding drag force is crucial for designing vehicles, aircraft, ships, and structures exposed to fluid flow, as well as for predicting object motion in fluids.

4. Using the Calculator

Tips: Enter fluid density (1.225 kg/m³ for air at sea level), velocity, drag coefficient (0.47 for sphere), and cross-sectional area. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical drag coefficient value?
A: It varies by shape: ~0.47 for sphere, ~1.05 for cylinder, ~1.28 for flat plate perpendicular to flow.

Q2: How does velocity affect drag force?
A: Drag increases with the square of velocity - double speed means 4x drag force.

Q3: What's the fluid density for water?
A: Pure water has density of ~1000 kg/m³ at 4°C. Seawater is ~1025 kg/m³.

Q4: How do I determine cross-sectional area?
A: For simple shapes, use geometric formulas (πr² for circle, width×height for rectangle). For complex shapes, use CAD software.

Q5: Does this formula work for all flow conditions?
A: This is for turbulent flow. For laminar flow, drag is proportional to velocity rather than velocity squared.