Mercurial > repos > public > sbplib
diff +rv/+time/BdfDerivative.m @ 1016:4b42999874c0 feature/advectionRV
Add lower level for boot-strapping to RungeKuttaExteriorRV
- Add a lower level to RungeKuttaExteriorRV for which bootstrapping starts, e.g start bootstrapping from time level 3 using a 3rd order BDF
- Clean up ResidualViscosity
author | Vidar Stiernström <vidar.stiernstrom@it.uu.se> |
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date | Fri, 07 Dec 2018 13:11:53 +0100 |
parents | +rv/+time/BDFDerivative.m@e547794a9407 |
children | 010bb2677230 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/+rv/+time/BdfDerivative.m Fri Dec 07 13:11:53 2018 +0100 @@ -0,0 +1,31 @@ +classdef BdfDerivative < handle + properties + coefficients + end + methods %TBD: Decide if the BDF order should be passed in construction + % and only a row of coefficients stored based on the order. + % There would still be an implicit dependancy on the number + % of vectors in v_prev and elements in coefficients. + % In addition, dt could be stored, but this would be + % inflexible if different step sizes are employed. + function obj = BdfDerivative() + obj.coefficients = obj.getBdfCoefficients(); + end + % Add asserts here? + function DvDt = evaluate(obj, v, v_prev, dt) + order = size(v_prev,2); + DvDt = (obj.coefficients(order,1)*v - sum(obj.coefficients(order,2:order+1).*v_prev,2))/dt; + end + end + methods(Static) + function c = getBdfCoefficients() + c = zeros(6,7); + c(1,1) = 1; c(1,2) = 1; + c(2,1) = 3/2; c(2,2) = 4/2; c(2,3) = -1/2; + c(3,1) = 11/6; c(3,2) = 18/6; c(3,3) = -9/6; c(3,4) = 2/6; + c(4,1) = 25/12; c(4,2) = 48/12; c(4,3) = -36/12; c(4,4) = 16/12; c(4,5) = -3/12; + c(5,1) = 137/60; c(5,2) = 300/60; c(5,3) = -300/60; c(5,4) = 200/60; c(5,5) = -75/60; c(5,6) = 12/60; + c(6,1) = 147/60; c(6,2) = 360/60; c(6,3) = -450/60; c(6,4) = 400/60; c(6,5) = -225/60; c(6,6) = 72/60; c(6,7) = -10/60; + end + end +end