CFD for Ballast Water & Bio-fouling Management

CFD for Ballast Water & Bio-fouling 

Management 

Vivek V. Ranade 

Catalysis, Reactors & Separation Unit (CReST) 

Chemical Engineering Division 

National Chemical Laboratory 

Pune 411008 

vv.ranade@ncl.res.in

OUTLINE 

• Ballast Water & Bio-fouling Management 

– Key issues 

• Computational Fluid Dynamics 

– What is CFD? 

– Methodology 

– Sample applications 

• Closure 

CFD for Ballast Water & Bio-fouling Management

BALLAST WATER/ BIO-FOULING 

• Filling/ draining: water hammer 

• Sloshing 

• Cleaning: high velocity jets 

• Mixing/ g exchange/ g ballast water treatment 

• Corrosion 

– Microbial 

– Flow assisted 

• Film formation: stability & break-up 

• Valves/ diodes/ piping circuit 

• Handling large quantities of water/ complex protocols 


BALLAST WATER EXCHANGE 

• Replace coastal water with open ocean water during 

a voyage 

– Emptying and refilling ballast tanks (sequential exchange) 

– Flow-through dilution/ continuous exchange 

• Concerns about 

– Biological effectiveness 

– Ship safety and operational issues 

• Excess bending moment/ shear stress, propeller immersion, 

minimum forward draft, sloshing … for sequential exchange 

• Flushing by fresh water, stratification, over pressurization … for 

continuous exchange 


SLOSHING 

From Lee et al., Ocean Engineering 34 (2007) 3–9 


• Use of Biocides 

WATER TREATMENT 

– Mixing of very small quantities in huge volume 

• Heat Treatment 

• UV 

• Ultrasonic Cavitation 

• Hydrodynamic Cavitation 

Exposure time distribution 

Pressure profiles, mixing 



• Filling/ draining: water hammer 

• Sloshing 

• Cleaning: high velocity jets 

• Mixing/ g exchange/ g ballast water treatment 

• Corrosion 

– Microbial 

– Flow assisted 

• Film formation: stability & break-up 

• Valves/ diodes/ piping circuit 

• Handling large quantities of water/ complex protocols 



• Detailed Modeling of Fluid Dynamics is Essential 

• Conventional Methods 

– Analytical fluid mechanics 

• Restricted to very simple flows 

– Scale models 

• Restricted validity/ difficult to extrapolate 

• Time consuming/ expensive 

• COMPUTATIONAL FLUID DYNAMICS (CFD) 


WHAT IS CFD? 

• Solution of Mass, Momentum and Energy Balances on Digital 

Computers 

• Major Features 

– No restrictive assumptions / approximations 

– Can handle complex geometry of industrial process equipment 

– Can incorporate variety of processes simultaneously 

• Can lead to: 

– Accurate insight of underlying fluid dynamics 

– A bridge between theory and experiments 

– Process data which can not be obtained from experiments 


COMPUTATIONAL FLOW MODELING 

• Enhanced understanding of theory through numerical 

experiments 

– Bridge between theory and experiments 

• Detailed analysis at early stage in design cycle for less money, 

less risk and less time 

• May provide data which is not possible to obtain experimentally 

– High pressure/ temperatures 

– Corrosive conditions 

• Screening of alternative design configurations 

• Sounds too good to be true ! Is there any catch some where? 


COMPUTATIONAL FLOW MODELING 

• Uncertainties / Limitations: 

– Inadequacies of the underlying mathematical model & input data 

• Turbulence 

• Multiphase flows 

• Complex Rheology 

• Chemical reactions 

– Inaccuracies of the numerical technique (discretisation and roundoff 

errors) 

– Computational constraints 

– Interpretation of results 

• Despite the Limitations, CFD has Enormous Potential ! 

– Necessary to develop appropriate methodology to harness this 

potential 


CReST @ NCL 

• Multi-scale Modeling Capabilities to Provide Complete 

Solutions for Reactor/ Product Engineering 

Simulation of Drop Impact on Flat Surface: 

Understanding wetting 

Separate model to 

simulate erosion of 

support hooks 

Top portion of industrial thermo-siphon loop 

reactor modeled using hybrid approach 

Simulation of Fluidized Bed Reactor: 

multi-scale approach 


METHODOLOGY 

• Development & Creative Use of 

Computational Models for Better 

Reactor, Process & Product 

Engineering 


• Optimizing Ballast Water 

Exchange Strategies 

APPLICATIONS 

J-type side 

Ballast Tank 

• Ballast Water Treatment 

Technology 

– Based on hydrodynamic 

cavitation 

CFD for Ballast Water & Bio-fouling Management 

• Modeling of cavitating flows 

• Devising effective 

cavitating it ti chamber h b ffor 

destruction of microbes 

• Adjust number density of 

cavities and intensity of 

collapse as per the 

requirements 

– Patented cavitating devices 

for water dis-infection

BALLAST WATER DISPOSAL 

• Flow-Through Exchange Method 

– 300% of a tank’s full capacity of clean water from the deep ocean 

must be pumped into each tank to achieve an acceptable 95% 

volumetric exchange. 

• Sequential q Exchange g ( (empty p y / refill) ) 

– Involves emptying tanks of high-risk ballast water at sea before 

refilling them with clean water from the deep ocean. 

• Dilution Method 

– Tank is partially filled and filling deep ocean water will dilute to 

original ballast water to 5% 

• Exchange to take place no less than 200 nautical miles from 

coast & at water depth of at least 200 m 


FLOW THROUGH EXCHANGE 

From Eames et al., Mar. Pollut. Bull. (2007), doi:10.1016/j.marpolbul.2007.10.032 


TYPES OF BALLAST TANKS 

Regular 

Double Bottom tank 

Hopper pp Upper pp Wing g 


J-type side 



DOUBLE BOTTOM BALLAST TANK 

Geometric Details : 

1. Volume of tank = 410 m3 2. Flow rate = 1000 m3 /hr 

9.12 m 

410 3 

3 

Tank volume m 

τ 

= = = 0. 

41hrs 

= 1476sec 

pumping rate 1000m 

hr 

CFD for Ballast Water & Bio-fouling Management 

30 m 

1.5 m

Outlet-1 

inlet 

Single port 

PORT CONFIGURATIONS 

Outlet-2 

Outlet-1

CFD for Ballast Water & Bio-fouling Management

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