Browsing by Author "Karunasena, HCP"

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item: Article-Full-text
A 3-D coupled Smoothed Particle Hydrodynamics and Coarse-Grained model to simulate drying mechanisms of small cell aggregates
(Elsevier, 2019) Rathnayaka, CM; Karunasena, HCP; Senadeera, W; Polwaththe-Gallage, HN; Gu, YT
Recently, meshfree-based computational modelling approaches have become popular in modelling biological phenomena due to their superior ability to simulate large deforma- tions, multiphase phenomena and complex physics compared to the conventional grid- based methods. In this article, small plant cell aggregates were simulated using a three di- mensional (3-D) Smoothed Particle Hydrodynamics (SPH) and Coarse-Grained (CG) coupled computational approach to predict the morphological behaviour during drying. The model predictions of these cell aggregate models have been compared qualitatively and quantita- tively through comparisons with experimental findings. The results show that the shrink- age and wrinkling behaviour of cell cluster models are in fairly good agreement with real cellular structures. The agreement between the cell aggregate model predictions and the experimental findings are closer in the high and medium moisture content values ( X / X 0 ≥0.3), than highly dried stages ( X / X 0 < 0.3). Further, optimisation and sensitivity studies have been conducted on model parameters such as particle resolution, smoothing length, mass transfer characteristics and wall forces. Overall, the 3-D nature of this model allows it to predict real 3-D morphological changes more realistically compared to the previous meshfree based 2-D cellular drying models. The proposed 3-D modelling approach has a higher potential to be used to model larger plant tissues with complicated physical and mechanical interactions as well as their multiscale interactions.
item: Article-Full-text
Application of a coupled smoothed particle hydrodynamics (SPH) and coarse-grained (CG) numerical modelling approach to study three-dimensional (3-D) deformations of single cells of different food-plant materials during drying
(2018) Rathnayaka, CM; Karunasena, HCP; Senadeera, W; Gu, YT
Numerical modelling has gained popularity in many science and engineering streams due to the economic feasibility and advanced analytical features compared to conventional experimental and theoretical models. Food drying is one of the areas where numerical modelling is increasingly applied to improve drying process performance and product quality. This investigation applies a three dimensional (3-D) Smoothed Particle Hydrodynamics (SPH) and Coarse-Grained (CG) numerical approach to predict the morphological changes of different categories of food-plant cells such as apple, grape, potato and carrot during drying. To validate the model predictions, experimental findings from in-house experimental procedures (for apple) and sources of literature (for grape, potato and carrot) have been utilised. The subsequent comaprison indicate that the model predictions demonstrate a reasonable agreement with the experimental findings, both qualitatively and quantitatively. In this numerical model, a higher computational accuracy has been maintained by limiting the consistency error below 1% for all four cell types. The proposed meshfree-based approach is well-equipped to predict the morphological changes of plant cellular structure over a wide range of moisture contents (10% to 100% dry basis). Compared to the previous 2-D meshfree-based models developed for plant cell drying, the proposed model can draw more useful insights on the morphological behaviour due to the 3-D nature of the model. In addition, the proposed computational modelling approach has a high potential to be used as a comprehensive tool in many other tissue morphology related investigations.
item: Conference-Full-text
novel application of adaptive fixed neighbourhood based sph (afn-sph) method to reduce computational time in meshfree based plant tissue drying models
(IEEE, 2020-07) Hansani, KGP; Kodithuwakku, AKCI; Baduge, S; Karunasena, HCP; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Smoothed Particle Hydrodynamics (SPH) is a popular meshfree method used in fluid dynamics which can be used to model higher deformable boundaries. However, compared to conventional grid-based methods, SPH based meshfree methods fundamentally consume higher computational time mainly due to the Nearest Neighbour Particle Searching (NNPS) algorithm. This becomes an obvious problem when modelling large 2-D and 3-D plant tissues as there is a higher number of interactions between particles. Very few attempts have been recently reported to obtain efficient computational performance when modelling the drying phenomena of plant tissues. Therefore, this research aims to introduce a novel application of the Adaptive Fixed Neighborhood based SPH (AFN-SPH) method, where the fixed neighbourhood with a radius of three times the smoothing length, get updated timely to represent the dynamic changes of the problem domain. It was observed that AFN-SPH is beneficial particularly to simulate plant tissues in extreme drying. Both qualitative and quantitative good agreements were observed in results compared to the conventional SPH techniques. Further, around 30%-40% of time reduction was obtained for different tissues. Therefore, the results indicated that this method can be used as a computationally efficient, meshfree based modelling approach applicable for problem domains with deforming boundaries.
item: Conference-Full-text
Numerical analysis and performance optimization of a flap-type oscillating wave surge converter in irregular waves
(IEEE, 2022-07) Manawadu, NHDS; Nissanka, ID; Karunasena, HCP; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Renewable energy plays a vital role in ensuring the sustainability of the world. Among different renewable energy sources, wave energy is one of the least-developed technologies. Out of the available Wave Energy Convertors (WEC) the Oscillating Wave Surge Converter (OWSC) is one of the most researched types of WECs due to its higher performance characteristics compared to many other WECs. In this background, this research focused on DualSPHysics-based numerical prediction of the energy conversion efficiency (ECE) and survivability of an OWSC in irregular waves observed in a selected coastal location of Sri Lanka. It was found that the Power take-off (PTO) damping coefficient, the density of the oscillating flap and the shape of the flap highly influence the ECE and the hydrodynamic forces on the WEC deciding its survivability. If the density of the flap is in the range of 400 - 600 kg/m 3 and its shape is more concave, the ECE increases significantly (about 25%) while improving its survivability. On the other hand, a significant reduction (25 to 47 %) in hydrodynamic forces could be achieved using cone or semicone-shaped flaps at the expense of ECE which would be a good alternative for high energetic seas.
item: Thesis-Abstract
Vision based cross sectional area estimator for industrial rubber profile extrusion process
(2014-07-31) Karunasena, HCP; Wickramarachchi, N
This thesis presents a research work which was carried out to develop a vision based cross sectional area profiling system suitable for continuous rubber profile extrusion processes. Rubber profiles are mostly used in rubber track production industry as a semi finished raw material. The linear volume of these profiles is a very important parameter for overall quality controlling of track production process. In order to maintain the linear volume it is a must that the cross section be measured and maintained within limits. Since the profile is continuously extruded by profile extruders, the profile cross section area measurement is best to be done in an online basis than off-line basis. A computer vision based online measurement system was developed which consists of a line laser projected on to the profile while a low cost digital camera observes the projection of this laser line on the profile. A vision software to be used in the system was also developed to interpret the captured cross section images in real time and produce numerical measurements and finally display on a computer with graphical user interface. The developed system is capable of measuring trapezoidal shape cross sections at a maximum rate of 6 measurements per second with repeatability error limited to }2% which preferably satisfies state of art rubber extrusion process quality controlling requirements. It can be concluded that with suitable further improvements, the technology can be integrated to extruder controlling systems as a feedback signal to control its output profile dimensions.