( 2 + x 6 )D(x)x] dx. in Java Drawer QR in Java ( 2 + x 6 )D(x)x] dx.

( 2 + x 6 )D(x)x] dx. generate, create qr-codes none on java projects .NET CF CD -values for ship sections In order to improve the predi ctions by eqs. (10.61) and (10.

62), we need to know more about CD values. It is dif cult to do this by theoretical means only. In the following text, we discuss what the important parameters are that in uence CD when the ship has zero forward speed.

Important factors are, for instance, free-surface effects, beam-to-draft ratio, bilge radius, Reynolds number, hull roughness, Keulegan-Carpenter (KC) number and three-dimensional ow effects. The KC number describes the effect of oscillatory ship motions. Let us consider a 2D section with transverse velocity Va sin((2 /T)t + ), where Va is.

20 8. X/Lpp 240 80. Simulated Measured Ship speed 15 6. Simulated Measured 4 120 40 60 2 Rudder angle Rate of turn 1 0 15 30. Yaw angle (deg.) 0 60. Ship speed (m/sec.) 0 2. Rate of turn (deg./sec.) -5 0 5 10.

Y/Lpp -2 -60 -20. -1 -10 -4 -120 -40 Yaw angle -2 -6 -15 -180 -6. Figure 10.18. Full-scale turn ing tests with a 30 m long version of the twin-hull vessel SSTH.

Simulated and measured trajectories and time history records are compared. LPP is the length between perpendiculars (Ishiguro et al. 1993).

. Rudder angle (deg.) 0 20. 90 Time (sec.). 408 Maneuvering Simulated Measured 30 6 Ship speed 15 Rate of turn (deg./sec.) 1 applet qr barcode 0 5 0 -5.

Rudder angle (deg.) 10 0. Ship speed (m/sec.) 0 2. Rate of turn Yaw angle (deg.) 10 0. Time (sec.). -10 -20. Rudder angle Yaw angle -30 -40. Figure 10.19. Full-scale zigz jar qr bidimensional barcode ag maneuver test with a 30 m long version of the twin-hull vessel SSTH.

Simulated and measured time history records are compared (Ishiguro et al. 1993)..

the velocity amplitude, T is the oscillation period, and is the phase. Then KC can be de ned as KC = Va T/Lc , where Lc is a characteristic length of the cross section, such as the beam of the section. How KC affects CD is discussed by Faltinsen.

(1990) and Sarpkaya and Isaac QR Code ISO/IEC18004 for Java son (1981). In the following part of this section, we also consider that the horizontal velocity of the cross section is time independent. This is the same as studying a xed cross section in a current and, therefore, this.

X/Lpp 4 15 Simulated Simulated Measured 3 X/Lpp 4 Measured 3 Ship speed (m/sec.). 2 0 0 -5 5 10 15 20 25 Time ( qr bidimensional barcode for Java sec.) 1. Y/Lpp Y/Lpp Figure 10.20. Full-scale cras h astern test with a 30 m long version of the twin-hull vessel SSTH.

Simulated and measured time history records are compared (Ishiguro et al. 1993)..

10.6 Nonlinear viscous effects for maneuvering in deep water at moderate speed 409 (t). 2. Beam-to-draft ratio effects Experimental results by Tanak a et al. (1982) show only a small effect of the height-to-length ratio on the drag coef cient for two-dimensional cross sections of rectangular forms. One exception is for small height-to-length ratios.

If one translates the results to ship cross sections, it implies that the beam-to-draft ratio B/D has a small in uence on the drag coef cient when B/D > 0.8..

(t). Figure 10.21. Simple vortex s ystem with an image ow above the free surface so that the rigid free-surface condition / z = 0 on z = 0 is satis ed.

(t) = circulation, V = in ow (ambient) velocity.. problem is considered. Two-di swing Denso QR Bar Code mensional ow is rst assumed. Three-dimensional effects are considered at the end.

. 3. Bilge radius effects Experimental results by Tanak QR Code for Java a et al (1982) show a strong effect of the bilge radius r on the drag coef cient. The bilge radius in uence on CD appears as CD = C1 e kr/D + C2 , where C1 and C2 are constants of similar magnitude and D is the draft. As an example, k may be 6.

Therefore, the increase of bilge radius will cause a substantial decrease of the drag coef cient. This effect is less relevant for high-speed hulls..

1. Free-surface effects The free surface at moderate QR-Code for Java Froude number tends to act as an in nitely long splitter plate. There is, of course, a difference because of the boundary layer on the splitter plate. However, there is no cross- ow either at the splitter plate or at the free surface.

Hoerner (1965) refers to CD -values for bodies with splitter plates of nite length in steady incident ow. The splitter plate causes a clear reduction of the drag coef cient. A simple explanation of why the free-surface presence affects the drag coef cient can partly be given by means of Figure 10.

21. The shed vorticity is represented by one single vortex of strength , which is a function of time. To account for the free-surface effect, one has to introduce an image vortex.

This ensures zero normal velocity on the free surface (see Figure 2.13 for a more complete picture of vortices). If the splitter plate (free surface) had not been there, instabilities would cause a Karman vortex street to develop behind the double body.

The image vortex illustrated in Figure 10.21 has a stronger effect on the motion of the real vortex than the vortices in a Karman vortex street behind the double body have on each other. Because there is a connection between the velocities of the shed vortices and the force on the body, we can understand why the free surface in uences the drag coef cient.

In the case of oscillating ambient ow at low amplitudes, the eddies will stay symmetric for the double body without a splitter plate. This means the free surface has the same effect in this case. However, we should note that the drag coef cient for ambient oscillatory ow with small amplitude is larger than that for steady incident (ambient) ow.

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