Mooring system design in anysim. Introduction... 2

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1 1 Mring system design in anysim CONTENTS Page Intrductin Analysis type DynFlatOutput CalcEqui and CalcEnvirEqui CalcPsSequence CalcFrceSequence Analysis type SingleLinePrepar Analysis type AllcateAnchrs Analysis type SystemStaticLad Sectin [EquiPsitin] Examples... 9

2 2 INTRODUCTION As frm release v10.3 anysim has extra ptins s it can als be used as the calculatin kernel f the new DynFlat. In the new DynFlat v10.0 the Java GUI calls a DLL cntaining anysim v10.3. Because the GUI f DynFlat has a number f interactive ptins fr the design f mring lines cq systems the utput f these ptins is nt available in the standard anysim utput file <rt>.rep. The GUI btains the results via the interfaces f the anysim DLL. T make the results available withut a GUI anysim writes them als t *.txt files. Nte that the mring design ptins can nly be applied t ne single vessel / mring system per run, cnfrm DynFlat. T use the extra mring design ptins a new key is added t the [General]-sectin in the anysim input file: Applicatin. The default value (when nt present) is: Simulatin. With this value a standard anysim simulatin is dne. Fr the extra mring design ptins the Applicatin-key shuld be: MringPrepar. When this ptin is selected a sectin must be present in the input file. The new sectin ffers the fllwing ptins via the key AnalysisType (as cmmn in anysim input files all inputted text strings are nt case-sensitive): AnalysisType = DynFlatOutput AnalysisType = SingleLinePrepar AnalysisType = AllcateAnchrs AnalysisType = SystemStaticLad With the DynFlatOutput ptin a <rt>.sta-file is created alng with the standard anysim <rt>.rep file. The <rt>.sta-file has the same cntents and layut as the existing *.sta-files f DynFlat. The ther 3 ptins SingleLinePrepar, AllcateAnchrs and SystemStaticLad are the interactive ptins frm the new DynFlat GUI. With these ptins there is als an anysim <rt>.rep-file, but it cntains nly an ech f the input. The results are nrmally returned via the interfaces f the anysim DLL t the GUI. T be able t use these ptins withut a GUI (with the anysim executable at the I-drive) the results are als written t files. These files have fixed names, s they are verwritten in case they already exist frm a previus run. The file names are: SingleLinePrepar: AllcateAnchrs: SystemStaticLad: SingleLinePrepar.txt AllcateAnchrs.txt SystemStaticLad.txt

3 3 1 ANALYSIS TYPE DYNFLOATOUTPUT With the analysis type DynFlatOutput there are 4 ptins which are activated with a tggle true / false. Any cmbinatin f these ptins is pssible. The ptins are available with the fllwing keys: CalcEqui CalcEnvirEqui CalcPsSequence CalcFrceSequence 1.1 CalcEqui and CalcEnvirEqui With the CalcEqui and CalcEnvirEqui ptins the equilibrium psitin f a mred vessel (X- and Y-psitin and heading) is calculated with r withut average envirnmental frces. The equilibrium psitin is fund with an iteratin prcedure. First the mring stiffness is linearized at the vessel s current psitin, then the new psitin fllws frm this stiffness and the sum f the average frces. At the new psitin the mring stiffness is again linearized, and s n, until the ffsets t a new psitin are smaller than the allwed errrs. The allwed errrs and the distances used fr the stiffness linearizatin can be given in the sectin [EquiPsitin], see the crrespnding paragraph in this dcument. The results are presented in 2 files: the <rt>.rep file, under the paragraph EQUILIBRIUM POSITION. This paragraph gives: initial CG and midship psitin; mring stiffness earth- and ship-fixed at the initial psitin; equilibrium CG and midship psitin; mring stiffness earth- and ship-fixed at the equilibrium psitin; the number f iteratins used t find the equilibrium psitin; the average wind, wave, current and ttal frces. the <rt>.sta file. This (DynFlat-type) file gives: a system review with vessel psitin, mring system type and its psitin n the vessel and the mring line prperties; an analysis review (which ptins have been chsen) and the settings fr the equilibrium iteratin prcedure; the static lad results per mring line with the pretensin values between 2 lines; the mring line design shapes (fr the given pretensins); the mring line shapes at the equilibrium psitin; a mring system summary table with tensins, hrizntal and vertical angles, catenary spans, anchr lads, lengths n the seabed, suspended lengths and line usage factrs (fractins f the break lads).

4 4 1.2 CalcPsSequence With the CalcPsSequence ptin the frces in the mring system are calculated fr a series f vessel psitins. These psitins are defined by surge, sway and yaw mtins w.r.t. the initial vessel psitin. These mtins can be given separately, fr example sway withut surge and yaw, r in any cmbinatin f these mtins. The fllwing keys are required fr the CalcPsSequence ptin: Nffset SurgeOffset SwayOffset YawOffset The results are given in the <rt>.sta file. Apart frm the utput as described in paragraph 2.1 there are als line shapes and system summary tables fr each psitin step and a summary table shwing fr each step the ttal earth- and ship-fixed mring system frces. 1.3 CalcFrceSequence With the CalcFrceSequence ptin the equilibrium psitin f the vessel is calculated fr a series f frces. These frces cmprise nly ship-fixed hrizntal frces (surge, sway and yaw). They can be given separately, fr example yaw mments withut surge and sway frces, r in any cmbinatin. The fllwing keys are required fr the CalcFrceSequence ptin: Nfrceseq FxFrce FyFrce MzFrce The results are given in the <rt>.sta file. Apart frm the utput as described in paragraph 2.1 there are als fr each frce cmbinatin the vessel psitin, the mring frces and the mring line shapes. At the end f the file there is a summary table with the line tensins.

5 5 2 ANALYSIS TYPE SINGLELINEPREPAR This analysis type is ne f the interactive functins where the DynFlat GUI btains the results via a DLL interface. In the GUI this functin is called after selectin f a line prperty which is t be pltted. This prperty can be: tensin at the fairlead; tensin at the anchr; vertical angle at the fairlead; line length n the seabed. When using anysim withut the DynFlat GUI such a prperty must be in the input file, althugh it is nt required fr the standalne anysim executable: all the abve mentined prperties are written t a file called SingleLinePrepar.txt. Nte that this is a fixed file name: the file will be verwritten after a rerun. S this analysis type requires the fllwing key in the -sectin with a dummy value: OutputPrperty = TensinAtFairlead The prperties are given frm a hrizntal ffset where the mring line is suspended vertically frm the fairlead up t a hrizntal ffset where the tensin at the fairlead equals the break lad f the line segment at the fairlead.

6 6 3 ANALYSIS TYPE ALLOCATEANCHORS This analysis type is als ne f the interactive functins where the DynFlat GUI btains the results via a DLL interface. The allcatin f the anchrs is a standard functinality f anysim when it initializes a mring system. Therefre there is n extra input required t d this, the -sectin cntains nly 1 key: AnalysisType = AllcateAnchrs The anchrs can be allcated based n 4 different inputs, see the Mring sectin in the anywiki. Nte that the anchr allcatin can be dne withut the need fr a Hyd-file: a bdy type Lad can als have a mring system attached t it. (This is dne in DynFlat because nly the vessel draft and psitin are knwn when the anchr allcatin is invked.) The results f the anchr allcatin are written t the file AllcateAnchrs.txt, which is als a fixed file name. Fr each line the fairlead and anchr lads and angles are given, tgether with, f curse, the anchr psitins, catenary spans, lengths n the seabed, suspended lengths and usage factrs.

7 7 4 ANALYSIS TYPE SYSTEMSTATICLOAD This analysis type is anther interactive functin where the DynFlat GUI btains the results via a DLL interface. It des the same as the CalcPsSequence ptin f the DynFlatOutput analysis, but there are differences: With the SystemStaticLad analysis it is als pssible t apply vertical ffsets t the vessel with the fllwing keys: HeaveOffset RllOffset PitchOffset (The DynFlat GUI prhibits the use f vertical ffsets in the DynFlatOutput analysis.) With the SystemStaticLad analysis the utput is written t the file SystemStaticLad.txt, which has a fixed file name. There is n <rt>.sta file. The DynFlat GUI makes a plt f ne f the restring frces and therefre needs t knw which restring frce t plt and in which system f axes (earth- r shipfixed). T use this functin with the standalne anysim executable 2 additinal keys must be present, but cntain nly dummy values as all restring frces are written t file, in bth the earth-fixed and ship-fixed system f axes. The fllwing can be used: RestringOutput = Fx InFlaterSc = True Just fr clarity: it seems that sme functinalities in anysim have a large verlap. This is due t the fact that the interactive functins SingleLinePrepar, AllcateAnchrs and SystemStaticLad were implemented first s that the calculatin kernel f the mring preparatin in Shuttle, StaMr, culd be replaced by anysim. At a later stage anysim was extended with the DynFlat functinalities s that the kernel f this prgram culd als be replaced by anysim.

8 8 5 SECTION [EQUIPOSITION] The [EquiPsitin]-sectin was added t anysim fr the CalcEqui and CalcEnvirEqui analysis types. This sectin may cntain the fllwing keys: MaxIteratins (default: 100) AllwedErrrEquiPs (default: 0.01 m) AllwedErrrEquiYaw (default: 0.1 deg) StiffnessXYStep (default: 1 m) StiffnessYawStep (default: 5 deg) With these keys the user can cntrl the accuracy f the calculated equilibrium psitin. Each key has a default value (see abve), s it is allwed t run the CalcEqui and CalcEnvirEqui analysis types withut this sectin. The keys f this sectin are nt part f the -sectin because they can als be used fr a vessel with a DP system (but this ptin has nt been validated yet).

9 9 6 EXAMPLES At I:\Applicatins\aNySIM\Benchmark_cases the fllwing examples are added, ne fr each analysis type (the benchmarks DynFlatOutput-* generate *.sta-files, the thers dn t): DynFlatOutput-CalcEqui DynFlatOutput-CalcEnvirEqui DynFlatOutput-CalcPsSequence DynFlatOutput-CalcFrceSequence DynFlat-SingleLinePrepar DynFlat-AllcateAnchrs DynFlat-SystemStaticLad Wageningen, Nvember 2010

10 10 MARITIME RESEARCH INSTITUTE NETHERLAND

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