About MoorDyn V2

Dear everyone,

Regarding the last time I asked a question on the forum about the use of moordynV2 I now have some new questions.

MoorDyn Waves and Currents input file
...any notes here...
--------------------------- WAVES -------------------------------------
3                    WaveKinMod  - type of wave input {0 no waves; 3 set up grid of wave data based on time series}
"waveelev.dat"       WaveKinFile - file containing wave elevation time series at 0,0,0
0.1                  dtWave      - time step to use in setting up wave kinematics grid (s)
0                    WaveDir     - wave heading (deg)
1    - X wave input type (0: not used; 1: list values in ascending order; 2: uniform specified by -xlim, xlim, num)
-850.0 -847.44 -844.88 -842.32 -839.76 -837.2 -834.64 -832.08 -829.52 -826.96 -824.4 -821.84 -819.28 -816.72 -814.16 -811.6 -809.04 -806.48 -803.92 -801.36 -798.8 -796.24 -793.68 -791.12 -788.56 -786.0 -783.44 -780.88 -778.3199999999999 -775.76 -773.2 -770.64 -768.08 -765.52 -762.96 -760.4 -757.84 -755.28 -752.72 -750.16 -747.6 -745.04 -742.48 -739.92 -737.36 -734.8 -732.24 -729.68 -727.12 -724.56 -722.0 -719.44 -716.88 -714.3199999999999 -711.76 -709.2 -706.64 -704.0799999999999 -701.52 -698.96 -696.4 -693.84 -691.28 -688.72 -686.16 -683.6 -681.04 -678.48 -675.92 -673.36 -670.8 -668.24 -665.6800000000001 -663.12 -660.56 -658.0 -655.44 -652.88 -650.3199999999999 -647.76 -645.2 -642.64 -640.0799999999999 -637.52 -634.96 -632.4 -629.84 -627.28 -624.72 -622.16 -619.6 -617.04 -614.48 -611.92 -609.36 -606.8 -604.24 -601.6800000000001 -599.12 -596.56 -594.0 -591.44 -588.88 -586.3199999999999 -583.76 -581.2 -578.64 -576.0799999999999 -573.52 -570.96 -568.4 -565.8399999999999 -563.28 -560.72 -558.16 -555.5999999999999 -553.04 -550.48 -547.9200000000001 -545.36 -542.8 -540.24 -537.6800000000001 -535.12 -532.56 -530.0 -527.44 -524.88 -522.3199999999999 -519.76 -517.2 -514.64 -512.0799999999999 -509.52 -506.96 -504.4 -501.84 -499.28 -496.71999999999997 -494.15999999999997 -491.59999999999997 -489.04 -486.48 -483.92 -481.36 -478.8 -476.24 -473.68 -471.12 -468.56 -466.0 -463.44 -460.88 -458.32 -455.76 -453.2 -450.64 -448.08 -445.52 -442.96 -440.4 -437.84 -435.28 -432.71999999999997 -430.15999999999997 -427.59999999999997 -425.03999999999996 -422.48 -419.92 -417.36 -414.8 -412.24 -409.68 -407.12 -404.56 -402.0 -399.44 -396.88 -394.32 -391.76 -389.2 -386.64 -384.08 -381.52 -378.96 -376.4 -373.84 -371.28 -368.71999999999997 -366.15999999999997 -363.59999999999997 -361.03999999999996 -358.48 -355.92 -353.36 -350.8 -348.24 -345.68 -343.12 -340.56 -338.0 -335.43999999999994 -332.88 -330.31999999999994 -327.76 -325.20000000000005 -322.64 -320.08000000000004 -317.52 -314.96000000000004 -312.4 -309.84000000000003 -307.28 -304.72 -302.15999999999997 -299.6 -297.03999999999996 -294.48 -291.91999999999996 -289.36 -286.79999999999995 -284.24 -281.67999999999995 -279.12 -276.55999999999995 -274.0 -271.43999999999994 -268.88 -266.31999999999994 -263.76 -261.19999999999993 -258.64 -256.08000000000004 -253.51999999999998 -250.96000000000004 -248.39999999999998 -245.84000000000003 -243.27999999999997 -240.72000000000003 -238.15999999999997 -235.60000000000002 -233.03999999999996 -230.48000000000002 -227.91999999999996 -225.36 -222.79999999999995 -220.24 -217.67999999999995 -215.12 -212.55999999999995 -210.0 -207.43999999999994 -204.88 -202.31999999999994 -199.76 -197.19999999999993 -194.64 -192.08000000000004 -189.51999999999998 -186.96000000000004 -184.39999999999998 -181.84000000000003 -179.27999999999997 -176.72000000000003 -174.15999999999997 -171.60000000000002 -169.03999999999996 -166.48000000000002 -163.91999999999996 -161.36 -158.79999999999995 -156.24 -153.67999999999995 -151.12 -148.55999999999995 -146.0 -143.43999999999994 -140.88 -138.31999999999994 -135.76 -133.19999999999993 -130.64 -128.08000000000004 -125.51999999999998 -122.96000000000004 -120.39999999999998 -117.84000000000003 -115.27999999999997 -112.72000000000003 -110.15999999999997 -107.60000000000002 -105.03999999999996 -102.48000000000002 -99.91999999999996 -97.36000000000001 -94.79999999999995 -92.24000000000001 -89.67999999999995 -87.12 -84.55999999999995 -82.0 -79.43999999999994 -76.88 -74.31999999999994 -71.75999999999999 -69.19999999999993 -66.63999999999999 -64.07999999999993 -61.51999999999998 -58.960000000000036 -56.39999999999998 -53.84000000000003 -51.27999999999997 -48.72000000000003 -46.15999999999997 -43.60000000000002 -41.039999999999964 -38.48000000000002 -35.91999999999996 -33.360000000000014 -30.799999999999955 -28.24000000000001 -25.67999999999995 -23.120000000000005 -20.559999999999945 -18.0 -15.43999999999994 -12.879999999999995 -10.319999999999936 -7.759999999999991 -5.199999999999932 -2.6399999999999864 -0.07999999999992724 2.480000000000018 5.039999999999964 7.600000000000023 10.159999999999968 12.720000000000027 15.279999999999973 17.840000000000032 20.399999999999977 22.960000000000036 25.519999999999982 28.08000000000004 30.639999999999986 33.200000000000045 35.75999999999999 38.32000000000005 40.879999999999995 43.440000000000055 46.0 48.56000000000006 51.120000000000005 53.680000000000064 56.24000000000001 58.80000000000007 61.360000000000014 63.92000000000007 66.48000000000002 69.03999999999996 71.60000000000002 74.15999999999997 76.72000000000003 79.27999999999997 81.84000000000003 84.39999999999998 86.96000000000004 89.51999999999998 92.08000000000004 94.63999999999999 97.20000000000005 99.75999999999999 102.32000000000005 104.88 107.44000000000005 110.0 112.56000000000006 115.12 117.68000000000006 120.24000000000001 122.80000000000007 125.36000000000001 127.92000000000007 130.48000000000002 133.03999999999996 135.60000000000002 138.15999999999997 140.72000000000003 143.27999999999997 145.84000000000003 148.39999999999998 150.96000000000004 153.51999999999998 156.08000000000004 158.64 161.20000000000005 163.76 166.32000000000005 168.88 171.44000000000005 174.0 176.55999999999995 179.12000000000012 181.68000000000006 184.24 186.79999999999995 189.36000000000013 191.92000000000007 194.48000000000002 197.03999999999996 199.5999999999999 202.16000000000008 204.72000000000003 207.27999999999997 209.83999999999992 212.4000000000001 214.96000000000004 217.51999999999998 220.07999999999993 222.6400000000001 225.20000000000005 227.76 230.31999999999994 232.8800000000001 235.44000000000005 238.0 240.55999999999995 243.12000000000012 245.68000000000006 248.24 250.79999999999995 253.36000000000013 255.92000000000007 258.48 261.03999999999996 263.60000000000014 266.1600000000001 268.72 271.28 273.8399999999999 276.4000000000001 278.96000000000004 281.52 284.0799999999999 286.6400000000001 289.20000000000005 291.76 294.31999999999994 296.8800000000001 299.44000000000005 302.0 304.55999999999995 307.1200000000001 309.68000000000006 312.24 314.79999999999995 317.3600000000001 319.9200000000001 322.48 325.03999999999996 327.60000000000014 330.1600000000001 332.72 335.28 337.8399999999999 340.4000000000001 342.96000000000004 345.52 348.0799999999999 350.6400000000001 353.20000000000005 355.76 358.31999999999994 360.8800000000001 363.44000000000005 366.0 368.55999999999995 371.1200000000001 373.68000000000006 376.24 378.79999999999995 381.3600000000001 383.9200000000001 386.48 389.03999999999996 391.60000000000014 394.1600000000001 396.72 399.28 401.8399999999999 404.4000000000001 406.96000000000004 409.52 412.0799999999999 414.6400000000001 417.20000000000005 419.76 422.31999999999994 424.8800000000001 427.44000000000005 430.0- X wave grid point data
1    - Y wave input type (0: not used; 1: list values in ascending order; 2: uniform specified by -xlim, xlim, num)
-750.0 -747.0 -744.0 -741.0 -738.0 -735.0 -732.0 -729.0 -726.0 -723.0 -720.0 -717.0 -714.0 -711.0 -708.0 -705.0 -702.0 -699.0 -696.0 -693.0 -690.0 -687.0 -684.0 -681.0 -678.0 -675.0 -672.0 -669.0 -666.0 -663.0 -660.0 -657.0 -654.0 -651.0 -648.0 -645.0 -642.0 -639.0 -636.0 -633.0 -630.0 -627.0 -624.0 -621.0 -618.0 -615.0 -612.0 -609.0 -606.0 -603.0 -600.0 -597.0 -594.0 -591.0 -588.0 -585.0 -582.0 -579.0 -576.0 -573.0 -570.0 -567.0 -564.0 -561.0 -558.0 -555.0 -552.0 -549.0 -546.0 -543.0 -540.0 -537.0 -534.0 -531.0 -528.0 -525.0 -522.0 -519.0 -516.0 -513.0 -510.0 -507.0 -504.0 -501.0 -498.0 -495.0 -492.0 -489.0 -486.0 -483.0 -480.0 -477.0 -474.0 -471.0 -468.0 -465.0 -462.0 -459.0 -456.0 -453.0 -450.0 -447.0 -444.0 -441.0 -438.0 -435.0 -432.0 -429.0 -426.0 -423.0 -420.0 -417.0 -414.0 -411.0 -408.0 -405.0 -402.0 -399.0 -396.0 -393.0 -390.0 -387.0 -384.0 -381.0 -378.0 -375.0 -372.0 -369.0 -366.0 -363.0 -360.0 -357.0 -354.0 -351.0 -348.0 -345.0 -342.0 -339.0 -336.0 -333.0 -330.0 -327.0 -324.0 -321.0 -318.0 -315.0 -312.0 -309.0 -306.0 -303.0 -300.0 -297.0 -294.0 -291.0 -288.0 -285.0 -282.0 -279.0 -276.0 -273.0 -270.0 -267.0 -264.0 -261.0 -258.0 -255.0 -252.0 -249.0 -246.0 -243.0 -240.0 -237.0 -234.0 -231.0 -228.0 -225.0 -222.0 -219.0 -216.0 -213.0 -210.0 -207.0 -204.0 -201.0 -198.0 -195.0 -192.0 -189.0 -186.0 -183.0 -180.0 -177.0 -174.0 -171.0 -168.0 -165.0 -162.0 -159.0 -156.0 -153.0 -150.0 -147.0 -144.0 -141.0 -138.0 -135.0 -132.0 -129.0 -126.0 -123.0 -120.0 -117.0 -114.0 -111.0 -108.0 -105.0 -102.0 -99.0 -96.0 -93.0 -90.0 -87.0 -84.0 -81.0 -78.0 -75.0 -72.0 -69.0 -66.0 -63.0 -60.0 -57.0 -54.0 -51.0 -48.0 -45.0 -42.0 -39.0 -36.0 -33.0 -30.0 -27.0 -24.0 -21.0 -18.0 -15.0 -12.0 -9.0 -6.0 -3.0 0.0 3.0 6.0 9.0 12.0 15.0 18.0 21.0 24.0 27.0 30.0 33.0 36.0 39.0 42.0 45.0 48.0 51.0 54.0 57.0 60.0 63.0 66.0 69.0 72.0 75.0 78.0 81.0 84.0 87.0 90.0 93.0 96.0 99.0 102.0 105.0 108.0 111.0 114.0 117.0 120.0 123.0 126.0 129.0 132.0 135.0 138.0 141.0 144.0 147.0 150.0 153.0 156.0 159.0 162.0 165.0 168.0 171.0 174.0 177.0 180.0 183.0 186.0 189.0 192.0 195.0 198.0 201.0 204.0 207.0 210.0 213.0 216.0 219.0 222.0 225.0 228.0 231.0 234.0 237.0 240.0 243.0 246.0 249.0 252.0 255.0 258.0 261.0 264.0 267.0 270.0 273.0 276.0 279.0 282.0 285.0 288.0 291.0 294.0 297.0 300.0 303.0 306.0 309.0 312.0 315.0 318.0 321.0 324.0 327.0 330.0 333.0 336.0 339.0 342.0 345.0 348.0 351.0 354.0 357.0 360.0 363.0 366.0 369.0 372.0 375.0 378.0 381.0 384.0 387.0 390.0 393.0 396.0 399.0 402.0 405.0 408.0 411.0 414.0 417.0 420.0 423.0 426.0 429.0 432.0 435.0 438.0 441.0 444.0 447.0 450.0 453.0 456.0 459.0 462.0 465.0 468.0 471.0 474.0 477.0 480.0 483.0 486.0 489.0 492.0 495.0 498.0 501.0 504.0 507.0 510.0 513.0 516.0 519.0 522.0 525.0 528.0 531.0 534.0 537.0 540.0 543.0 546.0 549.0 552.0 555.0 558.0 561.0 564.0 567.0 570.0 573.0 576.0 579.0 582.0 585.0 588.0 591.0 594.0 597.0 600.0 603.0 606.0 609.0 612.0 615.0 618.0 621.0 624.0 627.0 630.0 633.0 636.0 639.0 642.0 645.0 648.0 651.0 654.0 657.0 660.0 663.0 666.0 669.0 672.0 675.0 678.0 681.0 684.0 687.0 690.0 693.0 696.0 699.0 702.0 705.0 708.0 711.0 714.0 717.0 720.0 723.0 726.0 729.0 732.0 735.0 738.0 741.0 744.0 747.0 750.0- Y wave grid point data
1    - Z wave input type (0: not used; 1: list values in ascending order; 2: uniform specified by -xlim, xlim, num)
-200.0 -198.99532710280374 -197.99065420560748 -196.98598130841123 -195.98130841121494 -194.97663551401868 -193.97196261682242 -192.96728971962617 -191.9626168224299 -190.95794392523365 -189.9532710280374 -188.94859813084113 -187.94392523364485 -186.9392523364486 -185.93457943925233 -184.92990654205607 -183.92523364485982 -182.92056074766356 -181.9158878504673 -180.91121495327104 -179.90654205607476 -178.9018691588785 -177.89719626168224 -176.89252336448598 -175.88785046728972 -174.88317757009347 -173.87850467289718 -172.87383177570092 -171.86915887850466 -170.8644859813084 -169.85981308411215 -168.8551401869159 -167.85046728971963 -166.84579439252337 -165.84112149532712 -164.83644859813083 -163.83177570093457 -162.8271028037383 -161.82242990654206 -160.8177570093458 -159.81308411214954 -158.80841121495325 -157.803738317757 -156.79906542056074 -155.79439252336448 -154.78971962616822 -153.78504672897196 -152.7803738317757 -151.77570093457945 -150.7710280373832 -149.7663551401869 -148.76168224299064 -147.7570093457944 -146.75233644859813 -145.74766355140187 -144.7429906542056 -143.73831775700933 -142.73364485981307 -141.7289719626168 -140.72429906542055 -139.7196261682243 -138.71495327102804 -137.71028037383178 -136.70560747663552 -135.70093457943926 -134.696261682243 -133.69158878504672 -132.68691588785046 -131.6822429906542 -130.67757009345794 -129.67289719626166 -128.6682242990654 -127.66355140186916 -126.6588785046729 -125.65420560747663 -124.64953271028037 -123.64485981308411 -122.64018691588785 -121.63551401869158 -120.63084112149532 -119.62616822429906 -118.62149532710279 -117.61682242990653 -116.61214953271028 -115.60747663551402 -114.60280373831775 -113.59813084112149 -112.59345794392523 -111.58878504672897 -110.5841121495327 -109.57943925233644 -108.57476635514018 -107.57009345794393 -106.56542056074765 -105.5607476635514 -104.55607476635514 -103.55140186915887 -102.54672897196261 -101.54205607476635 -100.53738317757009 -99.53271028037382 -98.52803738317756 -97.5233644859813 -96.51869158878505 -95.51401869158877 -94.50934579439252 -93.50467289719626 -92.5 -91.49532710280373 -90.49065420560747 -89.48598130841121 -88.48130841121495 -87.47663551401868 -86.47196261682242 -85.46728971962617 -84.4626168224299 -83.45794392523364 -82.45327102803738 -81.44859813084112 -80.44392523364485 -79.43925233644859 -78.43457943925233 -77.42990654205607 -76.4252336448598 -75.42056074766354 -74.41588785046729 -73.41121495327103 -72.40654205607476 -71.4018691588785 -70.39719626168224 -69.39252336448598 -68.38785046728972 -67.38317757009344 -66.37850467289718 -65.37383177570092 -64.36915887850466 -63.364485981308405 -62.35981308411215 -61.35514018691589 -60.35046728971963 -59.345794392523345 -58.34112149532709 -57.33644859813083 -56.33177570093457 -55.32710280373831 -54.322429906542055 -53.3177570093458 -52.31308411214951 -51.30841121495325 -50.303738317756995 -49.29906542056074 -48.29439252336448 -47.28971962616822 -46.28504672897196 -45.280373831775705 -44.27570093457942 -43.27102803738316 -42.2663551401869 -41.261682242990645 -40.25700934579439 -39.25233644859813 -38.24766355140187 -37.242990654205585 -36.23831775700933 -35.23364485981307 -34.22897196261681 -33.22429906542055 -32.219626168224295 -31.214953271028037 -30.21028037383178 -29.205607476635493 -28.200934579439235 -27.196261682242977 -26.19158878504672 -25.18691588785046 -24.182242990654203 -23.177570093457945 -22.17289719626166 -21.1682242990654 -20.163551401869142 -19.158878504672884 -18.154205607476626 -17.14953271028037 -16.14485981308411 -15.140186915887853 -14.135514018691566 -13.130841121495308 -12.12616822429905 -11.121495327102792 -10.116822429906534 -9.112149532710276 -8.107476635514018 -7.102803738317732 -6.098130841121474 -5.093457943925216 -4.088785046728958 -3.0841121495327 -2.0794392523364422 -1.0747663551401843 -0.0700934579439263 0.9345794392523601 1.939252336448618 2.943925233644876 3.948598130841134 4.953271028037392 5.95794392523365 6.962616822429908 7.967289719626166 8.971962616822452 9.97663551401871 10.981308411214968 11.985981308411226 12.990654205607484 13.995327102803742 15.0- Z wave grid point data
--------------------------- CURRENT -------------------------------------
0                    CurrentMod  - type of current input {0 no current; 1 steady current profile described below}
z-depth     x-current      y-current
(m)           (m/s)         (m/s)
0.0             0.9          0.0
150             0.5          0.0
1000             0.25         0.0
1500           0.2           0.0
5000            0.15         0.0
--------------------- need this line ------------------

First is the WaveKinFile file, I am using the openfast output Wave1Elev, I think this also meets the requirements “file containing wave elevation time series at 0,0,0”, I would like to ask so that I would like to ask if this meets the requirement.
The second point is about the grid, the figure below is the top view of a 15MW mooring system.


image

The grid in x-direction is defined from -850m to 430m with a total of 501 points, y-direction is defined from -750m to 750m with a total of 501 points, and z-direction is defined from -200m to 15m with a total of 215 points, which is able to cover the whole mooring system, is it ok to do so?

Lastly, I am comparing the fairlead tension comparison chart of whether or not to consider WaterKin for an extreme sea state, does the trend fit the general pattern?


Best regards,

Hi, here are a few responses:

  1. Yes, the WaveElev1 output from OpenFAST should be suitable to use as the wave elevation input for MoorDyn.
  2. The grid you’ve set up seems fine to me, IF it doesn’t use too much memory. Often the wave kinematics have a small effect on the mooring lines, especially small at greater depths, so I’ve never tried this large a grid before. One simplification if your waves are along the x axis: you can just use one y grid point at y=0, then MoorDyn will assume the wave kinematics do not vary in y.
  3. The fairlead tension comparison looks odd to me because there seems to be a large mean tension difference. Wave kinematics tend to cause subtle changes in the tension amplitudes at the wave frequencies. I’ve never seen them cause a mean tension difference before.

Matt

Thank you for your reply, regarding the third point I have simulated a normal sea state condition, as you said, the fairlead difference is very small, may be due to the fact that this is an extreme sea state that I have caused such a big difference.
Best regards,