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September 22, 2024 at 11:52 am
bengalili
SubscriberHi.Â
I want to conduct a hydrostatic analysis on a Cylinder from the sea surface to the sea depth.Â
I need to get the force and moment exherted on the cylinder.Â
1. It works but in the LIS file I get very low (almost Zero) moment and force.
2. I also want to make sure that the moment is calculated arround the sea floor.Â
3. how do I control the drag coefficient and added mass coefficient?Appriciate the help.Â
example:
Diameter - 1m
sea depth - 5m
Wave period - 10 sec
JOB 0001 Â LINE
TITLE Â Â Â Â Â Â Â CYLINDER MODEL
OPTIONS LDOP GOON REST END
RESTART Â 1 Â 3
  01   COOR
  01  1         0.0    0.0    0.0
  01  2         -0.5    0.0    0.0
  01  3         -1.0    0.0    0.0
  01  4         -1.5    0.0    0.0
  01  5         -2.0    0.0    0.0
  01  6         -2.5    0.0    0.0
  01  7         -3.0    0.0    0.0
  01  8         -3.5    0.0    0.0
  01  9         -4.0    0.0    0.0
  01  10         -4.5    0.0    0.0
  01  11         -5.0    0.0    0.0
  01 999         0.0    0.0    -5.0
 END01
  02   ELM1
  02TUBE      (1)(1)(2)(1)(1)
  02TUBE      (1)(2)(3)(1)(1)
  02TUBE      (1)(3)(4)(1)(1)
  02TUBE      (1)(4)(5)(1)(1)
  02TUBE      (1)(5)(6)(1)(1)
  02TUBE      (1)(6)(7)(1)(1)
  02TUBE      (1)(7)(8)(1)(1)
  02TUBE      (1)(8)(9)(1)(1)
  02TUBE      (1)(9)(10)(1)(1)
  02TUBE      (1)(10)(11)(1)(1)
 END02
  02   FINI
  03   MATE
  03       1   7800
 END03
  04   GEOM
  04TUBE     1    1.0    0.1     0.0
 END04
  05   GLOB
  05DPTH   5.0
  05DENS   1025.0
  05ACCG   9.806   Â
 END05
  06   FDR1
  06PERD   1   1    10.0
  06DIRN   1   3   -180.0    0.0   180.0
 END06
  07   WFS1
 END07
  08   NONE
LIS OUTPUT:Â
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September 24, 2024 at 10:57 am
Shuangxing Du
Ansys EmployeeIn your nodal coordinate defintion (Node#1 ~ Node#11) and the tube element definition, the tubes' axial axis is on the mean water surface and along x-direction. Â
The force and moment are output with respect to the COG of the structure, i.e. (Xg, Yg, Zg). If you want the moment to be output with respect to another reference point, i.e. (Xr, Yr, Zr), please manually do the calculation with the additional cross product term:
(Mrx, Mry, Mrz) = (Mx, My, Mz) + (Xr -Xg, Yr-Yg, Zr-Zg) x (Fx, Fy, Fz)
where (Mx, My, Mz) is the moment with respect to COG, (Fx, Fy, Fz) is the force with the respect to COG.
The translational drag and added mass coefficients can be input by CONT data record, see below and see 8.3. Geometric Property Data Record (ansys.com)
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