scholarly journals Simulasi CFD pada Kapal Planing Hull

Kapal ◽  
2019 ◽  
Vol 16 (3) ◽  
pp. 123-128 ◽  
Author(s):  
Samuel Samuel ◽  
Andi Trimulyono ◽  
Ari Wibawa Budi Santosa

Akurasi dalam memprediksi hambatan kapal adalah salah satu aspek penting dalam mendesain lambung kapal. Secara umum, hambatan kapal dengan type planing lebih rumit daripada type displacement. Planing hull memiliki karakteristik unik seperti trim, heave, hard-chine, Froude number tinggi dan dead-rise angle. Gaya hidrodinamik pada planing hull lebih dominan daripada gaya hidrostatik. Analisis numerik menggunakan Finite Volume Method (FVM) dipilih untuk menyelesaikan masalah hidrodinamik. Dalam penelitian ini, persamaan (RANS Reynolds-Averaged Navier-Stokes) digunakan untuk menggambarkan model turbulensi dengan k-ε. Secara umum, pemodelan Volume of Fluid (VOF) menggunakan aliran multiphase Euler yang diasumsikan air dan udara sebagai phase. Tujuan dari penelitian ini adalah untuk memperkenalkan perhitungan kapal type planing hull untuk memprediksi hambatan kapal dan seakeeping. Studi validasi ini dilakukan dengan menggunakan eksperimen Fridsma hullform. Hasil pada penelitian ini menunjukkan bahwa simulasi numerik pada jenis planing hull dapat diprediksi dengan akurasi yang cukup baik.

2020 ◽  
Vol 4 (1) ◽  
pp. 24-34
Author(s):  
Abubakar Fathuddiin ◽  
Samuel Samuel ◽  
Kiryanto Kiryanto ◽  
Aulia Widyandari

ABSTRAKPrediksi hambatan kapal tipe planing lebih rumit dibanding dengan tipe displacement, hal ini disebabkan oleh gaya hidrodinamis yang lebih dominan pada bagian bawah kapal. Karakteristik hambatan kapal tipe planing sangat dipengaruhi oleh gerakan trim dan heave. Selain itu, bentuk hullform juga mempengaruhi hambatan kapal; seperti sudut dead-rise, chine, strip, stephull, dan lain-lain. Solusi untuk memprediksi hambatan kapal dengan menggunakan Finite Volume Method (FVM). Persamaan RANS (Reynolds- Averaged Navier-Stokes) dengan model turbulensi k-ε untuk memprediksi aliran turbulen dan Volume of Fluid (VOF) untuk mempresentasikan aliran 2 fasa. Pada penelitian ini digunakan metode overset mesh untuk memprediksi hambatan kapal agar mendapatkan akurasi yang baik. Hasil simulasi hambatan menunjukkan trend yang baik. Pada kecepatan tinggi, prediksi hambatan tidak memiliki hasil yang baik. Solusi yang ditawarkan pada Numerical ventilation problem (NVP) adalah dengan menggunakan metode phase replacement.Kata kunci: CFD, planing hull, RANS, overset mesh, NVP ABSTRACTThe prediction of planing hull resistance is more complicated than the displacement hull. It is caused by the more dominant hydrodynamic force at the bottom of the ship. The planing hull resistance characteristics are strongly influenced by trim and heave movements. In addition, the shape of the hullform also affects the ship's resistance, such as dead-rise angle, chine, strip, stephull, and others. The solution to predict ship resistance is by using the Finite Volume Method (FVM). RANS (Reynolds-Averaged Navier-Stokes) equation k-ε turbulence model was used to predict turbulent flow and Volume of Fluid (VOF) to present 2 phase flow. In this study, the overset mesh method was used to predict ship resistance in order to get good accuracy. Resistance simulation results showed a good trend. At high speeds, the prediction of resistance did not have good results. The solution offered in the Numerical ventilation problem (NVP) was to use the phase replacement method.Keywords: CFD, planing hull, RANS, overset mesh, NVP


Author(s):  
Roque Corral ◽  
Javier Crespo

A novel high-order finite volume method for the resolution of the Navier-Stokes equations is presented. The approach combines a third order finite volume method in an unstructured two-dimensional grid, with a spectral approximation in the third dimension. The method is suitable for the resolution of complex two-dimensional geometries that require the third dimension to capture three-dimensional non-linear unsteady effects, such as those for instance present in linear cascades with separated bubbles. Its main advantage is the reduction in the computational cost, for a given accuracy, with respect standard finite volume methods due to the inexpensive high-order discretization that may be obtained in the third direction using fast Fourier transforms. The method has been applied to the resolution of transitional bubbles in flat plates with adverse pressure gradients and realistic two-dimensional airfoils.


Author(s):  
Sheguang Zhang ◽  
Daniel Liut ◽  
Kenneth Weems ◽  
Woei-Min Lin

A 3-D Finite Volume method (FV3D) is developed and applied to green water problems. The Navier-Stokes (N-S) equations are discretized with the 3-D finite volume method on collocated Cartesian grids. The free surface motion is captured with the Volume of Fluid (VOF) method. The velocity and pressure fields are solved by the SIMPLER scheme with an alternating direction implicit solver. FV3D is validated against existing experimental and numerical results for tank sloshing and ship green-water-on-deck cases. This method is applicable to calculation of the green water effect on advanced wave-piercing hull forms.


Author(s):  
Xingwei Zhang ◽  
Chaoying Zhou

Fundamental research on interaction between flow and structure is presented for computation the fluid dynamics of different two-dimensional oscillating models. The Navier-Stokes equations are solved using finite volume method. A multigrid mesh method which was applied to the situation of flow past the stagnating or vibrating cylinder is developed to simulate this type of flow. The interactive results between flow and structure rigid cylinders have been present. The computation fluid dynamic codes mainly with low Reynolds RANS solver are used to solve the impressible viscous Navier-Stokes equations. Finite volume method which is coupled with conformal hybrid mesh method is developed to simulate this type of flow. Numerical investigation focused on the response and the fluid forces on the cylinders and also observed the different shedding model in the wake. The numerical results are compared in detail with recent experimental and computational work. Present numerical comparison also showed that solution using different turbulence model will make the result have a little discrepancy and each turbulence model has respective characteristics in numerical solution on the vortex-induced vibration of the cylinder. In addition, the formation of the 2P vortex shedding model through the lock-in region and the beginning of the shedding model transformation in numerical calculation from 2S model to 2P model has been analyzed.


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