basalstress

PURPOSE ^

BASALSTRESS - evaluates the basal stress

SYNOPSIS ^

function [sx,sy,smag]=basalstress(md)

DESCRIPTION ^

BASALSTRESS -  evaluates the basal stress

   The basal stress is computed according to the following formula: 
   sigma=drag^2*Neff^r*vel^s
   where:
    Neff is the effective pressure (Neff=rho_ice*g*thickness+rho_water*g*bed),
    r=q/p
    s=1/p
    p and q being friction coefficients found in the literature (Paterson).

   Usage:
      [Fx,Fy,Fmag]=basalstress(md)

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function [sx,sy,smag]=basalstress(md)
0002 %BASALSTRESS -  evaluates the basal stress
0003 %
0004 %   The basal stress is computed according to the following formula:
0005 %   sigma=drag^2*Neff^r*vel^s
0006 %   where:
0007 %    Neff is the effective pressure (Neff=rho_ice*g*thickness+rho_water*g*bed),
0008 %    r=q/p
0009 %    s=1/p
0010 %    p and q being friction coefficients found in the literature (Paterson).
0011 %
0012 %   Usage:
0013 %      [Fx,Fy,Fmag]=basalstress(md)
0014 
0015 %Compute effective pressure
0016 Neff=md.rho_ice*md.g*md.thickness+md.rho_water*md.g*md.bed;
0017 Neff(find(Neff<0))=0.1;
0018 r=md.q./md.p;
0019 s=1./md.p;
0020 dragel=(md.drag(md.elements(:,1))+md.drag(md.elements(:,2))+md.drag(md.elements(:,3)))/3;
0021 Neffel=(Neff(md.elements(:,1))+Neff(md.elements(:,2))+Neff(md.elements(:,3)))/3;
0022 velel=(md.vel(md.elements(:,1))+md.vel(md.elements(:,2))+md.vel(md.elements(:,3)))/3/md.yts;
0023 vxel=(md.vx(md.elements(:,1))+md.vx(md.elements(:,2))+md.vx(md.elements(:,3)))/3/md.yts;
0024 vyel=(md.vy(md.elements(:,1))+md.vy(md.elements(:,2))+md.vy(md.elements(:,3)))/3/md.yts;
0025 
0026 sx=dragel.^2.*Neffel.^r.*velel.^(s-1).*vxel;
0027 sy=dragel.^2.*Neffel.^r.*velel.^(s-1).*vyel;
0028 smag=sqrt(sx.^2+sy.^2);

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