Welcome to the homepage of IITM-RANS3D. It is an in-house CFD code developed at the Department of Ocean Engineering, IIT Madras. The code has been developed with the aim of handling complex wave-structure interaction simulations in large domains over a long period of time.
IITM-RANS3D is a multiphase code based on the single-fluid formulation of the incompressible Navier-Stokes equations. The Navier-Stokes equations are solved using a semi-explicit solver over a Cartesian staggered mesh. Multiphase treatment is achieved using the VOF method. Waves are generated through a Dirichlet input from the in-house fully non-linear potential theory (FNPT) code IITM-FNPT2D. Turbulence effects are modeled using the RANS philosophy. Structures are modeled using the fictitious-domain method.
Key Features and Strengths:
- Strong pressure-velocity coupling realized through the staggered mesh.
- CICSAM scheme optimized for speed on Cartesian meshes through operator-splitting.
- One-way coupled with IITM-FNPT2D thus enabling very high fidelity generation of a wide range of waves.
- One-way coupling with IITM-FNPT2D allows for truncation of the RANS domain to the near-field of the structure. This saves computational effort by delegating the inviscid wave simulations to FNPT.
- Wave simulations are energy preserving even for large domains (say GWK: 350m x 5m x 7m) and for long time (say >~100 s).
- Turbulence effects characterizing wave-structure interaction modeled using the standard k-ε model.
- Fictitious-domain modeling of the structure precludes modifying the mesh topology in the vicinity of the structure thus enabling the use of Cartesian meshes even for complex structures.
- Parallelized using MPI. Capable of fully utilizing the computational resources offered by multi-core standalone compute nodes (SMA-shared memory architecture) as well as the VSR group server and IITM’s AQUA cluster (DMA-distributed memory architecture).
- Option for importing structure geometries through *.STL files.
- Capable of simulating forward speed problems.
- RANS as well as VOF formulation only applicable to Cartesian meshes.
- Diffuse interface treatment of the solid region ; implicit imposition of the slip boundary condition.
- Algebraic VOF scheme-based estimation of the interface location ; interface placement is not geometric.
Limitations (specific to release 1.0):
- No turbulence modeling ; laminar solver.
- Time discretization is first order forward Euler ; pressure and diffusion terms treatment is second-order.
- Two-phase Navier-Stokes formulation is non-conservative.
- Capable of handling complex albeit fixed structures.
- FNPT-RANS coupling is one-way.
Work in progress and future updates:
- Conservative solver to handle breaking jets.
- 6-DoF rigid solver, mooring lines & coupling for aero elasticity.
- Compressible air phase modelling for OWC, entrapped air.
Typical Application problems:
(2) Steep solitary wave interacting with a cylinder
(3) Focused waves interacting with a moonpool
(4) Steep solitary wave breaking over a sloping ridge
(5) Forward motion of the cylinder
IITM – RANS3D is an open source. We welcome researchers to either use it or change for your needs. Any clarification and suggestions you may reach us: Dr. Shaswat Saincher: firstname.lastname@example.org or Myself: email@example.com
Version 1: IITM-RANS3D_1.0 (Non Conservative Solver)
Version 2: Expected Release – mid January 2022.
Developed and tested by:
Dr. Shaswat Saincher (PostDoc)
Mr. Hari Ram N. (M.S. student) – Solitary wave interaction with vegetation
Ms. Jemi Jeya (Ph.D. student) – Regular waves interacting with pile-supported caisson
Mr. Harish Selvam (Ph.D. student) – Tsunami-like bores interacting with buildings
Ms. Shrushti Shirsat (M.Tech student) – Aero-hydrodynamics of bottom-profiled OWC chambers