Description

This function queries a Surface Particle (Mie) scatter model for its percent area coverage (PAC) value.  The PAC value is calculated by adding up the cross sectional areas of spherical particles for the particle distribution function of the model (the number of particles of a given diameter over a range of particle sizes).

Syntax

pac = GetMieScatterPercentAreaCoverage(  mieNode )

Parameters

pac (Double)

Returned percent area coverage value for the specified Surface Particle (Mie) scatter model.

mieNode As Long

Node number of the Surface Particle (Mie) scatter model being queried.  If mieNode is not a Surface Particle (Mie) scatter type, then the function halts with an error message reporting that the specified entity is not of the correct type.

Example

The example below shows a case where we update the CL and maximum particle size for a Mie model with a 1246C particulate distribution inside a loop and report the PAC value calculated by the GetMieScatterPercentAreaCoverage function as well as the PAC value from a commonly used approximation function.

Sub Main

    ClearOutputWindow()

    'Scatter model we are querying

    Dim mieNode As Long

    mieNode = FindScatter( "Mie Model" )

    Print "Mie model: " & Chr(9) & GetScatterName( mieNode )

    Print ""

    'Range of CLs we want to scan

    Dim startCl As Double, endCL As Double, clStep As Double

    Dim nSteps As Long

    startCl = 200

    endCL   = 1000

    nSteps  = 10

    clStep  = (endCL - startCl)/nSteps

    'Retrieve the model's parameters

    Dim tMie As T_MIESCATTER

    GetMieScatter( mieNode, tMie )

    'Header

    Print "CL";

    Print "PAC";

    Print "Approx"

    'Loop over CLs, update the model, print the CL, PAC and approximate PAC

    Dim curCL As Double, pac As Double

    For curCL = startCl To endCL Step clStep

        tMie.CleanLevel = curCL

        tMie.MaxDia     = curCL

        SetMieScatter( mieNode, tMie )

        pac = GetMieScatterPercentAreaCoverage( mieNode )

        Print curCL;

        Print pac;

        Print CalcApproxPAC( curCL )

    Next

End Sub

Function CalcApproxPAC( ByVal in_cl As Double ) As Double

    'Approximate PAC calculation

    Dim pac As Double

    pac = -7.245 + 0.926 * (Log10(in_cl)^2)

    pac = 10^pac

    Return pac

End Function

See Also

Scatter Script Commands