Pochai, Nopparat

Preferred name

Pochai, Nopparat

Alternative Name

Pochai, N.

Main Affiliation

School of Science

nopparat.po@kmitl.ac.th

Now showing 1 - 10 of 33

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A numerical treatment of a mathematical model of ground water flow in rice field near marine shrimp aquaculture farm
(2012-01-01)
Pochai, N.
;
Pongnoo, N.
The high level salinity in soil is a main problem of a plant grows less in rice field near marine shrimp aquaculture farm. The salinity in soil and ground water flow are required for soil quality assessments. The modeling often involves numerical methods to solve the equations. In this research, two mathematical models are used to simulate the salinity in the ground with varied flow velocity. The first is a potential flow model that provides the velocity field of the ground water flow. The second is a dispersion model, where the commonly used governing factor is the twodimensional dispersion equation that gives the salinity fields. In the simulation process, we used the finite difference method for the both models. Finally, we present a numerical simulation that confirms the results of the technique. © 2010 Published by Elsevier Ltd.
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Mathematical simulation of a groundwater management in a drought area using an implicit finite difference method
(2019-12-01)
Pongnu, Nattawut
;
Pochai, Nopparat
The groundwater management is required to solve the problem of lack water resources in many drought areas for agricultural usage. In this study, we propose a groundwater flow model and a groundwater management model that provide the pumping rates and the injection rates respectively. The groundwater model is providing the hydraulic head that gives the groundwater level. The implicit finite difference method is used to approximate the groundwater flow directions. The objective of groundwater flow management model is the minimum cost of injection rates. These are then subjected to optimal management of the water injection stations to achieve minimum cost. The numerical experiments are also given.
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Numerical models of nitrogen compound measurements in a stream with removal mechanism using Saulyev technique with cubic spline interpolation
(2019-11-17)
Vongkok, Areerat
;
Pochai, Nopparat
Nutrient pollution negatively affects ecology, environment and human health, due to excess contaminated nitrogen in aquatic ecosystems. Nitrogen has various forms, such as organic nitrogen, ammonia, nitrite, and nitrate. Nitrogen removal mechanisms are important for nitrogen compound pollutant control. Microbial agents provide an alternative for nitrogen removal and are implemented by natural removal mechanisms. For pollution level measurements, data collection from actual measurement processes can be only limitedly collected in some situations. The mathematical models play a role in data approximation that can describe relations of processes and reactions. Six numerical models in one-dimensional nitrogen pollutant and nitrogen remover measurement in a stream are proposed. The proposed models are combined with total nitrogen with a removal mechanism, organic nitrogen, ammonia, nitrite, nitrate, and nitrogen remover dispersion models. These models are implemented through use of an efficient numerical technique, which is the unconditionally explicit Saulyev finite difference technique, associated with the cubic spline interpolation to initial and left boundary conditions through practical simulations. All six models related to nitrogen compound measurements in a stream with removal mechanism models give accurately approximated solutions. The proposed numerical models can be applied to other realistic problems.
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A numerical treatment of nondimensional form of water quality model in a nonuniform flow stream using Saulyev scheme
(2011-11-24)
Pochai, Nopparat
The stream water quality model of water quality assessment problems often involves numerical methods to solve the equations. The governing equation of the uniform flow model is one-dimensional advection-dispersion-reaction equations (ADREs). In this paper, a better finite difference scheme for solving ADRE is focused, and the effect of nonuniform water flows in a stream is considered. Two mathematical models are used to simulate pollution due to sewage effluent. The first is a hydrodynamic model that provides the velocity field and elevation of the water flow. The second is a advection-dispersion-reaction model that gives the pollutant concentration fields after input of the velocity data from the hydrodynamic model. For numerical techniques, we used the Crank-Nicolson method for system of a hydrodynamic model and the explicit schemes to the dispersion model. The revised explicit schemes are modified from two computation techniques of uniform flow stream problems: forward time central space (FTCS) and Saulyev schemes for dispersion model. A comparison of both schemes regarding stability aspect is provided so as to illustrate their applicability to the real-world problem. © 2011 Nopparat Pochai.
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Simulation of salinity intrusion in chao phraya river by a developed mathematical model and MacCormack scheme with cubic spline interpolation
(2019-01-01)
Kulmart, Khemisara
;
Pochai, Nopparat
The purpose of this research was to develop a mathematical model for controlling salinity intrusion in Chao Phraya River, Thailand, using one-dimensional advection-diffusion equation. There have been many research studies that applied a mathematical model called dispersion model to estimating salinity concentration. Our proposed dispersion model is simple, using very few parameters, but can simulate salinity intrusion adequately. We used MacCormack scheme to approximate salinity intrusion and cubic spline interpolation technique to approximate field data including initial salinity concentrations and the concentrations at the left boundary. The MacCormack scheme and Cubic Spline interpolation technique were quite suitable for approximating real data, and the proposed mathematical model was able to predict salinity intrusion adequately.
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Optimal homotopy asymptotic solution for exothermic reactions model with constant heat source in a porous medium
(2015-01-01)
Mabood, Fazle
;
Pochai, Nopparat
The heat flow patterns profiles are required for heat transfer simulation in each type of the thermal insulation. The exothermic reaction models in porous medium can prescribe the problems in the form of nonlinear ordinary differential equations. In this research, the driving force model due to the temperature gradients is considered. A governing equation of the model is restricted into an energy balance equation that provides the temperature profile in conduction state with constant heat source on the steady state. The proposed optimal homotopy asymptotic method (OHAM) is used to compute the solutions of the exothermic reactions equation.
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Numerical Simulation to Air Pollution Emission Control near an Industrial Zone
(2017-01-01)
Oyjinda, Pravitra
;
Pochai, Nopparat
A rapid industrial development causes several environment pollution problems. One of the main problems is air pollution, which affects human health and the environment. The consideration of an air pollutant has to focus on a polluted source. An industrial factory is an important reason that releases the air pollutant into the atmosphere. Thus a mathematical model, an atmospheric diffusion model, is used to estimate air quality that can be used to describe the sulfur dioxide dispersion. In this research, numerical simulations to air pollution measurement near industrial zone are proposed. The air pollution control strategies are simulated to achieve desired pollutant concentration levels. The monitoring points are installed to detect the air pollution concentration data. The numerical experiment of air pollution consisted of different situations such as normal and controlled emissions. The air pollutant concentration is approximated by using an explicit finite difference technique. The solutions of calculated air pollutant concentration in each controlled and uncontrolled point source at the monitoring points are compared. The air pollutant concentration levels for each monitoring point are controlled to be at or below the national air quality standard near industrial zone index.
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Erratum to: Effects of prescribed heat flux and transpiration on MHD axisymmetric flow impinging on stretching cylinder (Continuum Mech. Thermodyn., 10.1007/s00161-016-0519-9)
(2016-11-01)
Mabood, Fazle
;
Lorenzini, Giulio
;
Pochai, Nopparat
;
Ibrahim, Sheikh Muhammad
Unfortunately, one of the author names was incorrectly published in the original version and the same is corrected here. The original publication is corrected as well.
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A numerical treatment of smoke dispersion model from three sources using fractional step method
(2012-04-02)
Konglok, Sureerat A.
;
Pochai, Nopparat
The source of air pollutant is the main of conducting emission inventories. The smoke discharging from industrial plant is a principle reason of air pollution problem. In this research, the comparison of difference numbers of chimney as the same emission rate of the pollutant is considered. The fractional step method is used for solving the smoke dispersion model. It is shown that air quality in a control area by the case of three point sources is better than two point sources.
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Homotopy analysis method for radiation and hydrodynamic-thermal slips effects on MHD flow and heat transfer impinging on stretching sheet
(2018-01-01)
Mabood, Fazle
;
Lorenzini, Giulio
;
Pochai, Nopparat
;
Shateyi, Stanford
This article deals with the analytical study of MHD flow and heat transfer over a permeable stretching sheet via homotopy analysis method (HAM). The effect of thermal radiation is included in the energy equation, while velocity and thermal slips are included in the boundary conditions. The governing boundary layer equations are transformed into a set of ordinary differential equations by means of similarity transformations. The effects of different parameters on the flow field and heat transfer characteristics are examined. The results obtained were shown to compare well with the numerical results and for some special cases with the published data available in the literature, which are in favorable agreement.

Pochai, Nopparat

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