hydraulics (version 0.2.0)

manningt: Solves the Manning Equation for water flow in an open channel

Description

This function solves the Manning equation for water flow in an open channel with a trapezoidal shape. This is a modification of the code prepared by Irucka Embry in his iemisc package. Specifically the iemisc::manningtrap, iemisc::manningrect, and iemisc::manningtri were combined and adapted here for more limited cases commonly used in classroom exercises.Some auxiliary variables in the iemisc code are not included here (shear stress, and specific energy), as these will be done separately. A cross-section figure is also available.

Usage

manningt(
  Q = NULL,
  n = NULL,
  m = NULL,
  Sf = NULL,
  y = NULL,
  b = NULL,
  units = c("SI", "Eng")
)

Arguments

Q

numeric vector that contains the flow rate [m^3/s or or ft^3/s]

n

numeric vector that contains the Manning roughness coefficient

m

numeric vector that contains the side slope of the channel (m:1 H:V) [unitless]

Sf

numeric vector that contains the slope of the channel [unitless]

y

numeric vector that contains the water depth [m or ft]

b

numeric vector that contains the channel bottom width [m or ft]

units

character vector that contains the system of units [options are SI for International System of Units and Eng for English (US customary) units. This is used for compatibility with iemisc package.

Value

Returns a list including the missing parameter:

• Q - flow rate

• V - flow velocity

• A - cross-sectional area of flow

• P - wetted perimeter

• R - hydraulic radius

• y - flow depth (normal depth)

• b - channel bottom width

• m - channel side slope

• Sf - slope

• B - top width of water surface

• n - Manning's roughness

• yc - critical depth

• Fr - Froude number

• Re - Reynolds number

Examples

# NOT RUN {
#Solving for flow rate, Q, trapezoidal channel: SI Units
manningt(n = 0.013, m = 2, Sf = 0.0005, y = 1.83, b = 3, units = "SI")
#returns Q=22.2 m3/s

#Solving for roughness, n, rectangular channel: Eng units
manningt(Q = 14.56, m = 0, Sf = 0.0004, y = 2.0, b = 4, units = "Eng")
#returns Manning n of 0.016

#Solving for depth, y, triangular channel: SI units
manningt(Q = 1.0, n = 0.011, m = 1, Sf = 0.0065, b = 0, units = "SI")
#returns 0.6 m normal flow depth

# }