svFSI residual definitions

[Tanmay Shidhore]

Hello,

I am trying to figure out the definitions of residual quantities in the histor.dat file outputted by svFSI. I saw that there was a section in the documentation for svsolver that gives a description of what each column means and I was wondering if there was something similar available for svFSI. Thanks.

[Weiguang Yang]

Here is a part of histor.dat file.

Eq N-i T dB Ri/R0 R/Ri lsIt dB %t
----------------------------------------------------------
FS 1-1 1.9970 [ 0 1.00000 6.53E-3] [ 6 -8 21]
MS 1-1 2.1150 [ 0 1.00000 0.00000] [ 0 0 0]
FS 1-2 3.8709 [ -15 1.59E-1 6.07E-3] [ 5 -9 10]
MS 1-2 3.9870 [ 0 1.00000 0.00000] [ 0 0 0]
FS 1-3 5.9909 [ -48 3.79E-3 4.86E-3] [ 5 -9 17]

To my understanding, the first column shows the solver type: FS represents the FSI solver and MS represents the mesh solver. The second column N-i shows the time step count N - the ith nonlinear iteration for that time step. The third column shows the CPU time. The fourth, fifth and sixth columns show residual changes. dB: 20*log_10(Ri/R1), where Ri and R1 is the L^2 norm of the residual vectors at iteration i and 1 respectively for each time step. R0 is the L^2 norm of the residual vectors at t=0. R is the final L^2 norm of the residual after solving the linear system. The last three columns show information about the linear solver that solves AU=R, in which A = [K D;-G L] and
! G = -D^t. IsIt: iterations in the linear solver. dB is the final residual norm relative to the previous iteration in decibel scale: db= 5log_10(Rf(i)/Rf(i-1)). %t shows % time spent on the linear solver.

[Tanmay Shidhore]

Thank you!