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*FOURIER,FILE=PATH/FOURIER_DTB_FILE
Data format:
One line with 6 parameters, followed by one line with 2 parameters, as follows:
TFIN DT BETA ORD IFLAG ICOEF
IGR_1 .. IGR_N
Status:
Optional (time-domain dynamic analyses).
Purpose:
To use Fourier coefficients to assess hydrodynamic forces.
Restriction:
The groups of elements IGR(1) to IGR(N) must have been previously defined.
Details:
| Parameter | Description |
|---|---|
| FOURIER_DTB_FILE | Path and filename of the external data file providing the Fourier coefficients used to calculate the wave kinematics. See the example below for details on the file content. |
| TFIN | Total duration wave simulation (s) |
| DT | Time step for hydrodynamic force calculation |
| BETA | Coefficient for wave decomposition (memory effect in irregular wave) : 0.25 is recommended |
| ORD | Max order of Fourier coefficients (5 is the maximum for the DHI database) |
| IFLAG | Option for calculation : IFLAG = 0, Hydrodynamic forces issued from Fourier method deduced from static position of elements are not used in dynamic calculation IFLAG = 1 Hydrodynamic forces issued from Fourier method deduced from static position of elements are used in dynamic calculation IFLAG = 2 (NOT YET AVAILABLE) Hydrodynamic forces issued from Fourier method deduced from current position of elements are used in dynamic calculation |
| ICOEF | Coefficient used for sliding window calculation : width = ICOEF * Tmax (Tmax is the largest half period of the wave signal) : 1.5 is recommended |
| IGR_1 | Identification number of the first group of elements. |
| IGR_N | Identification number of the last group of elements. |
External data file format:
The FOURIER_DTB_FILE file has the following format:
| Row No. | Parameter | Description |
|---|---|---|
| 1 | MAX_DEG | Maximum order of harmonics defined in the file |
| 2 | NB_KSTAR | Number of values for k (where k = k/D) |
| 3 | KSTAR(1) ... KSTAR(NBKSTAR) | Values for k* parameters |
| 4 | NB_KC | Number of values for KC |
| 5 | KC(1) ... KC(NBKC) | Values for KC parameters |
| 6 | NB_ALPHA | Number of values for alpha (U_Cur / U_Wave) |
| 7 | ALPHA(1) ... ALPHA(NB_ALPHA) | Values for alpha parameters |
| Followed by a number of NB_KSTAR x NB_KC x NB_ALPHA rows, each row including (3+4xMAX_DEG+2) columns, as follows: | ||
| Column 1 | KSTAR(I) | |
| Column 2 | KC(J) | |
| Column 3 | ALPHA(K) | |
| Columns 4 to (MAXDEG + 4) | CD(0,I,J,K) ... CD(MAXDEG,I,J,K) | Drag coefficient harmonics amplitude for KSTAR(I), KC(J) and ALPHA(K) |
| Columns (MAXDEG + 5) to (2xMAXDEG + 5) | CL(0,I,J,K) ... CL(MAXDEG,I,J,K) | Lift coefficient harmonics amplitude for KSTAR(I), KC(J) and ALPHA(K) |
| Columns (2xMAXDEG + 6) to (3xMAXDEG + 5) | PHCD(1,I,J,K) ... PHCD(MAXDEG,I,J,K) | Drag coefficient harmonics phase for KSTAR(I), KC(J) and ALPHA(K) |
| Columns (3xMAXDEG + 5) to (4xMAXDEG + 5) | PHCL(1,I,J,K) ... PHCL(MAXDEG,I,J,K) | Lift coefficient harmonics phase for KSTAR(I), KC(J) and ALPHA(K) |
An example of content that is to be input for the last group of NB_KSTAR x NB_KC x NB_ALPHA rows is shown below:
| Kstar(1) kc(1) alpha(1) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
|---|
| Kstar(1) kc(1) alpha(2) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
| .... |
| Kstar(1) kc(1) alpha(nb_alpha) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
| Kstar(1) kc(2) alpha(1) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
| Kstar(1) kc(2) alpha(2) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
| .... |
| Kstar(1) kc(2) alpha(nb_alpha) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
| .... |
| Kstar(1) kc(nb_kc) alpha(1) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
| Kstar(1) kc(nb_kc) alpha(2) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
| .... |
| Kstar(1) kc(nb_kc) alpha(nb_alpha) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
| .... |
| Kstar(nb_kstar) kc(nb_kc) alpha(1) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
| Kstar(nb_kstar) kc(nb_kstar) alpha(2) Cd(0) ..Cd(MAX_DEG) Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
| .... |
| Kstar(nb_kstar) kc(nb_kstar) alpha(nb_alpha) Cd(0) ..Cd(MAX_DEG) |
| Cl(0)..Cl(MAX_DEG) phid(1) ..phid(MAX_DEG) phil(1)..phil(MAX_DEG) |
