Contents

function [tbx,tby,tb,eta] = CalcBasalTraction(CtrlVar,UserVar,MUA,F,options)

  [tbx,tby,tb,eta] = CalcBasalTraction(CtrlVar,UserVar,MUA,F,options)

Calculates basal traction from basal velocity using the sliding law.

Returns either nodal or integration point values depending on the values of the logical optional input variables

CalcNodalValues=[true|false]
CalcIntegrationPointValues=[true|false]

Also returns the effective viscosity at integration points, if CalcIntegrationPointValues=true;

Note: This can only be used to calculate basal traction when using the SSTREAM and the Hybrid flow approximation. This will not return correct results for the SSHEET approximation!

Note: The calculation at integration points is fully consistent with the way basal traction is calculated in Ua.

arguments
    CtrlVar struct
    UserVar struct
    MUA     struct
    F       {mustBeA(F,{'struct','UaFields','numeric'})}

    options.CalcNodalValues  logical = false
    options.CalcIntegrationPointValues  logical = true
    options.CalvingFrontColor char = "b"
    options.GroundingLineColor char = "r"
    options.PlotResults=false;


end

eta=[];


if isempty(F.ub)
    tbx=[]; tby=[] ; tb=[];
    return
end


if options.CalcNodalValues

    [tbx,tby,tb] = CalcBasalTractionAtNodes(CtrlVar,UserVar,MUA,F) ;

    if options.PlotResults

        FindOrCreateFigure(" nodal traction ") ;
        [cbar,~,Par]=QuiverColorGHG(F.x/CtrlVar.PlotXYscale,F.y/CtrlVar.PlotXYscale,tbx,tby) ;
        PlotGroundingLines(CtrlVar,MUA,F.GF,[],[],[],color=options.GroundingLineColor);
        PlotCalvingFronts(CtrlVar,MUA,F,color=options.CalvingFrontColor);
        PlotMuaBoundary(CtrlVar,MUA,"k--");
        title(cbar,"(kPa)")
        title("Basal tractions at nodal points")


        UaPlots(CtrlVar,MUA,F,tb,FigureTitle=" magnitude of basal traction at nodal points ")
        title("magnitude of basal traction at nodal points")

    end
end

% Note if both nodal and integration point values are calculated, only the integration point values are returned.
if options.CalcIntegrationPointValues

    CtrlVar.uvhMatrixAssembly.ZeroFields=false;
    CtrlVar.uvhMatrixAssembly.Ronly=false;
    CtrlVar.OnlyCalcBasalDragAndEffectiveViscosity=true ;
    [tbx,tby,tb,eta] = CalcBasalTractionAtIntegrationPoints(CtrlVar,UserVar,MUA,F,F) ;


    if options.PlotResults

        [F.xint,F.yint] = CalcIntegrationPointsCoordinates(MUA) ;
        fbt=FindOrCreateFigure(" integration points traction ") ;  clf(fbt);

        if options.CalcNodalValues  % if nodal values were also calculated, make them comparable by using same scaling as before.
            Par.QuiverSameVelocityScalingsAsBefore=1;
        else
            Par=[];
        end
        cbar=QuiverColorGHG(F.xint/CtrlVar.PlotXYscale,F.yint/CtrlVar.PlotXYscale,tbx,tby,Par) ;
        hold on
        PlotGroundingLines(CtrlVar,MUA,F.GF,[],[],[],color=options.GroundingLineColor);
        PlotCalvingFronts(CtrlVar,MUA,F,color=options.CalvingFrontColor);
        PlotMuaBoundary(CtrlVar,MUA,"k--");
        title(cbar,"(kPa)")
        title("Basal tractions at integration points")

        UaPlots(CtrlVar,MUA,F,tb,FigureTitle=" magnitude of basal traction at integration points")
        title("magnitude of basal traction at integration points")

        UaPlots(CtrlVar,MUA,F,eta,FigureTitle=" effective viscosity")
        title("Effective viscosity at integration points")

    end
end

end

local functions

function [tbx,tby,tb] = CalcBasalTractionAtNodes(CtrlVar,UserVar,MUA,F)

narginchk(4,4)

Calculates basal traction from basal velocity using the sliding law.

Returns nodal values

Note: There is a slight inconsistency with respect to how this is done internally in Ua in the sense that the floating mask is here evaluated at nodes, whereas internally this is done at integration points.

hf=F.rhow*(F.S-F.B)./F.rho ;
He = HeavisideApprox(CtrlVar.kH,F.h-hf,CtrlVar.Hh0);  % 1
delta = DiracDelta(CtrlVar.kH,F.h-hf,CtrlVar.Hh0) ;

[tbx,tby] = ...
    BasalDrag(CtrlVar,MUA,He,delta,F.h,F.B,F.S-F.B,F.rho,F.rhow,F.ub,F.vb,F.C,F.m,F.uo,F.vo,F.Co,F.mo,F.ua,F.va,F.Ca,F.ma,F.q,F.g,F.muk,F.V0);

tb=sqrt(tbx.^2+tby.^2);

end



function [tbx,tby,tb,eta] = CalcBasalTractionAtIntegrationPoints(CtrlVar,UserVar,MUA,F0,F1)

narginchk(5,5)

Calculates basal traction from basal velocity using the sliding law at integration points

RunInfo=[];

[~,~,~,~,tbx,tby,eta]=uvhMatrixAssembly(UserVar,RunInfo,CtrlVar,MUA,F0,F1) ;

tb=sqrt(tbx.^2+tby.^2);

end

Published with MATLAB® R2024b