# Terminal Velocity: NLE with 'if' condition
# Verified Solution: vt = 0.015782
# Ref.: Comput. Appl. Eng. Educ. 6: 174, 1998

f(vt) = vt^2*(3*CD*rho)-4*g*(rhop-rho)*Dp
rho = 994.6
g = 9.80665
rhop = 1800
Dp = 0.208e-3
vis = 8.931e-4
Re = Dp*vt*rho/vis
CD = if (Re < 0.1) then (24/Re) else (24*(1+0.14*Re^0.7)/Re)

vt(min) = 0.0001
vt(max) = 0.05
Single Nonlinear Equation Preview

f(vt)=vt2·(3·CD·ρ)4·g·(ρpρ)·Dp
ρ=994.6
g=9.80665
ρp=1800
Dp=0.000208
vis=0.0008931
Re=Dp·vt·ρvis
CD=if(Re<0.1,24Re,24·(1+0.14·Re0.7)Re)
Solution Guess Boundaries
vt(min)=0.0001
vt(max)=0.05

Program validated. Ready to Solve.

Nonlinear Equation Solution

 VariableValuef(x)Initial valueInitial f(x)
1vt0.015781618-9.6e-90.049652.1e+1
2rho994.6 994.6 
3g9.80665 9.807 
4rhop1800 1800 
5Dp0.000208 0.000208 
6vis0.0008931 0.0008931 
7Re3.6556385 11.5 
8CD8.8426583 3.701 

Root Finding Plot

Chart

Settings and Hints

 Name/SourceValueType
1 Number of equations 8 Setting
2 Implicit equations 1 Setting
3 Explicit equations 7 Setting
4 Elapsed time 0.000 ms Setting
5 Solution method Brent Setting
6 Tolerance F 1e-7 Setting
7 Max iterations 150 Setting
8 #@chart_size = 428,300 Default (array)
9 #@report_fix_digits = 8 Default (integer)
10 #@report_show_source = true Default (boolean)
11 #@report_show_header = false Default (boolean)
12 #@report_show_charts = true Default (boolean)
13 #@report_show_settings = true Default (boolean)

Messages

 SeverityDescription
1Info-Infor- Implicit variables (1) vt
2Info-Infor- Explicit variables (7) rho, g, rhop, Dp, vis, Re, CD
3Info-Infor- All variables (8) vt, CD, rho, g, rhop, Dp, vis, Re

Source

# Terminal Velocity: NLE with 'if' condition
# Verified Solution: vt = 0.015782
# Ref.: Comput. Appl. Eng. Educ. 6: 174, 1998

f(vt) = vt^2*(3*CD*rho)-4*g*(rhop-rho)*Dp
rho = 994.6
g = 9.80665
rhop = 1800
Dp = 0.208e-3
vis = 8.931e-4
Re = Dp*vt*rho/vis
CD = if (Re < 0.1) then (24/Re) else (24*(1+0.14*Re^0.7)/Re)

vt(min) = 0.0001
vt(max) = 0.05