Drag Force Calculator

Compute Drag Force, Velocity, or Area. Enter drag coefficient

  
 

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Select fluid: 
Select calculation:   
   
Fluid Density: 
Drag Coefficient, C: 
Reference Area, A: 
Velocity, V: 
Force, F: 
©2014 LMNO Engineering,  Research, and Software, Ltd.  http://www.LMNOeng.com

Drag force calculator units: cm=centimeter, ft=feet, g=gram, hr=hour, kg=kilogram, km=kilometer, lb=pound, m=meter, N=Newton, s=second

Introduction
Drag force is caused by a fluid (such as water or air; or any liquid or gas) impinging upon an object. The drag force is a function of the fluid velocity and density along with the object's reference area and drag coefficient. The drag coefficient may further be a function of the Reynolds number. Reynolds number depends on the fluid density, viscosity, and velocity as well as the object's characteristic length.

Drag Force Equation (Blevins, 2003 and Munson et al., 1998 and others)

F = 0.5 C ρ A V2

Notation
Our drag force calculation allows you to use a variety of units with all of the conversions completed internally. The units below are consistent units for the drag force equation.
A = Reference area as (see figures below), m2.
C = Drag coefficient (see figures below), unitless.
F = Drag force, N.
V = Velocity, m/s.
ρ = Density of fluid (liquid or gas), kg/m3.

Drag coefficients for various objects (photographs taken by LMNO Engineering).

Tree (C values from Munson et al., 1998)
A=Tree frontal area
C=0.43 if V=10 m/s (36.0 km/h, 22.4 mph)
C=0.26 if V=20 m/s (72.0 km/h, 44.7 mph)
C=0.20 if V=30 m/s (108 km/h, 67.1 mph)
Tree
 Flag (C values from Munson et al., 1998)
A=DL
C=0.07 if L/D=1
C=0.12 if L/D=2
C=0.15 if L/D=3
Flag 		Thin Rectangular Plate (C from Blevins, 2003)
Flow coming at the sign
A=DL
C=1.05 if L/D=1.0
C=1.10 if L/D=2.0
C=1.12 if L/D=4.0
C=1.20 if L/D=8.0
C=1.22 if L/D=10.0
C=1.22 if L/D=12.0
C=1.33 if L/D=17.8
C=1.90 if L/D=infinity
Thin rectangular plate

 

Messages
"Need Density > 0", "Need C > 0", "Need Area > 0", "Need Velocity > 0", "Need Force > 0".

References
Blevins, Robert D. 2003. Applied Fluid Dynamics Handbook. Krieger Publishing Co.

Munson, Bruce R., Donald F. Young, and Theodore H. Okiishi. 1998. Fundamentals of Fluid Mechanics. John Wiley and Sons, Inc. 3ed.

 

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Please contact us for consulting or questions about drag force.

LMNO Engineering, Research, and Software, Ltd.
7860 Angel Ridge Rd.   Athens, Ohio 45701  USA   Phone: (740) 707-2614
LMNO@LMNOeng.com    https://www.LMNOeng.com

 

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Drag Force Calculation with built-in drag coefficient values

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