Description Usage Arguments Details Value Author(s) References See Also Examples
View source: R/forcedparameters.R
Parameters required for forced convection equation and heat exchange estimation.
1 | forcedparameters(V = 1, L = 0.1, Ta = 20, shape = "hcylinder")
|
V |
Air velocity in metres/second. Used in call to Reynolds(). Default is 0.1. |
L |
Characteristic dimension in metres. Default value is 0.1. |
Ta |
Air temperature in degrees celsius. Used in call to Reynolds(). Default is 20. |
shape |
"sphere", "hplate", "vplate", "hcylinder", "vcylinder" to denote shape and orientation. h=horizontal, v=vertical. Default shape is "hcylinder" |
Gates (2003) describes coefficients that characterise the base and exponent values used to calculate Nusselt numbers from Reynolds number as: c*Re^n. This function will return those parameters.
A vector of length two, with values c and n.
Glenn J Tattersall
Blaxter, 1986. Energy metabolism in animals and man. Cambridge University Press, Cambridge, UK, 340 pp.
Gates, DM. 2003. Biophysical Ecology. Dover Publications, Mineola, New York, 611 pp.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 | ## The function is currently defined as
function (V = 1, L = 0.1, Ta = 20, shape = "hcylinder")
{
Re <- Reynolds(V, L, airviscosity(Ta))
if (shape == "vplate" | shape == "hplate")
shape <- "plate"
if (shape == "vcylinder" | shape == "hcylinder")
shape <- "cylinder"
if (shape == "plate") {
c = 0.595
n = 0.5
}
if (shape == "sphere") {
c = 0.37
n = 0.6
}
if (shape == "cylinder" & Re >= 0.4 & Re < 4) {
c <- 0.891
n = 0.33
}
if (shape == "cylinder" & Re >= 4 & Re < 40) {
c <- 0.821
n = 0.385
}
if (shape == "cylinder" & Re >= 40 & Re < 4000) {
c <- 0.615
n = 0.466
}
if (shape == "cylinder" & Re >= 4000 & Re < 40000) {
c <- 0.174
n = 0.618
}
if (shape == "cylinder" & Re >= 40000 & Re < 4e+05) {
c <- 0.024
n = 0.805
}
coeffs <- c(c, n)
names(coeffs) <- c("c", "n")
coeffs
}
# Example:
V<-1
L<-0.1
Ta<-20
shape="hcylinder"
forcedparameters(V, L, Ta, shape)
shape="vcylinder"
forcedparameters(V, L, Ta, shape)
shape="hplate"
forcedparameters(V, L, Ta, shape)
shape="vplate"
forcedparameters(V, L, Ta, shape)
shape="sphere"
forcedparameters(V, L, Ta, shape)
|
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