MoorDyn v1 w/ Matlab Returning Zeros

[Ian-Ammerman]

I am trying to run MoorDyn v1 with Matlab. I downloaded the source .zip from the releases page as well as the pre-compiled .dll file MoorDyn_Win64.dll and added it to the source folder. I added a subfolder "Mooring" with the following lines.txt file for the OC4 semi-submersible platform:

--------------------- MoorDyn Input File ------------------------------------ MoorDyn input file of the mooring system for OC4 Semi-submersible True Echo echo the input file data (flag) ----------------------- LINE TYPES ------------------------------------------ LineType Diam MassDen EA BA/-zeta Can Cat Cdn Cdt (-) (m) (kg/m) (N) (Pa-s/-) (-) (-) (-) (-) main 0.0766 113.35 7.536E8 -1.0 0.8 0.25 2.0 0.4 ---------------------- NODE PROPERTIES -------------------------------- Node Type X Y Z M V FX FY FZ CdA CA (-) (-) (m) (m) (m) (kg) (m^3) (kN) (kN) (kN) (m^2) (-) 1 Fixed 418.8 725.383 -200.0 0 0 0 0 0 0 0 2 Fixed -837.6 0.0 -200.0 0 0 0 0 0 0 0 3 Fixed 418.8 -725.383 -200.0 0 0 0 0 0 0 0 4 Vessel 20.434 35.393 -14.0 0 0 0 0 0 0 0 5 Vessel -40.868 0.0 -14.0 0 0 0 0 0 0 0 6 Vessel 20.434 -35.393 -14.0 0 0 0 0 0 0 0 ---------------------- LINES ---------------------------------------- Line LineType UnstrLen NumSegs NodeAnch NodeFair Flags/Outputs (-) (-) (m) (-) (-) (-) (-) 1 main 835.35 20 1 4 - 2 main 835.35 20 2 5 - 3 main 835.35 20 3 6 - ---------------------- SOLVER OPTIONS ----------------------------------------- 0.001 dtM - time step to use in mooring integration (s) 3.0e6 kBot - bottom stiffness (Pa/m) 3.0e5 cBot - bottom damping (Pa-s/m) 60 TmaxIC - maximum simulation time for IC convergence 4.0 CdScaleIC - factor for scaling drag coefficients for IC convergence 0.001 threshIC - threshold for IC convergence (-) ---------------------- OUTPUTS ----------------------------------------- ------------------------- need this line --------------------------------------

I pulled the test script from the v1 user guide and am running it with the source code directory active (and all subfolders added to path):

clear all; close all; clc;

%% Setup % Close out MoorDyn library if still open if libisloaded('MoorDyn_Win64') calllib('MoorDyn_Win64','LinesClose');
unloadlibrary MoorDyn_Win64;
end

X = zeros(6,1); % platform position XD = zeros(6,1); % platform velocity N = 10; % number of coupling time steps dt = 0.5; % coupling time step size (time between MoorDyn calls) Ts = zeros(N,1); % time step array FairTens1 = zeros(N+1,1); % array for storing fairlead 1 tension time series FLines_temp = zeros(1,6); % going to make a pointer so LinesCalc can modify FLines FLines_p = libpointer('doublePtr',FLines_temp); % access returned value with FLines_p.value

%% Initialization [notfound,warnings] = loadlibrary('MoorDyn_Win64','MoorDyn.h'); % load MoorDyn DLL mooring_status = calllib('MoorDyn_Win64','LinesInit',X,XD); % initialize MoorDyn

%% Simulation XD(1) = 1; % give platform 0.1 m/s velocity in surge

for i=1:N calllib('MoorDyn_Win64', 'LinesCalc', X, XD, FLines_p, Ts(i), dt) % some MoorDyn time stepping FairTens1(i+1) = calllib('MoorDyn_Win64','GetFairTen',1); % store fairlead 1 tension forces(i,:) = FLines_p.Value X = X + XDdt % update position Ts(i+1) = dti; % store time end

%% Ending calllib('MoorDyn_Win64','LinesClose'); % close MoorDyn unloadlibrary MoorDyn_Win64; % unload library (never forget to do this!)

Moordyn loads in fine and converges correctly, giving the following in the console:

(MoorDyn-initiated console window)

Running MoorDyn (v1.01.02C, 2021-02-14) Copyright (c) Matt Hall, licensed under GPL v3. Creating mooring system. 3 fairleads, 3 anchors, 0 connections. Finalizing ICs using dynamic relaxation (4X normal drag) Fairlead tensions converged to 0.1% after 4 seconds.

However, after running the script the forces output are all zero and the FairTens1 values are all -1. I'm not sure if the issues lies in my input text file or in how I am installing MoorDyn.