Angle Of 45o Research Articles

Research of cooling performance in combined jet flow channels using different nanofluids

In this work, heat transfer from the cube and circular hollow-shaped copper plate surfaces with a constant heat flux of 1000 W/m2 was numerically investigated by using a combination of the cross-flow-impinging jet. Numerical research was performed by solving the energy and Navier-Stokes equations as three-dimensional and steady, using the Ansys-Fluent computer program with the k-ε turbulence model. In order to direct the combined jet flow in the channel to the heated surfaces, the fins with 30o and 60o angles were placed in the channel horizontally with the impinging jet surface. While the channel height ( H) is 4D, the distance of the fin from the jet inlet ( N) is 2D. Fluids used in the channels are water, 0.02% GO-water and 2% diamond-water. The upper and lower surfaces of the channel and the fin are adiabatic and the flow Reynolds number range is 5000–15,000. The results of the work were compared with the experimental results of the studies in the literature and they were found to be consistent with each other. The results were presented as the mean Nu number and mean surface temperature variations for each model surface. Besides, the velocity and temperature contour distributions of the combined jet flow along the channel for diamond-water nanofluid were evaluated. Also, performance evaluation coefficient and average Nu number (Num), and surface temperature values (Tm) were evaluated at different Reynolds numbers for all three patterned surfaces in the channels. At Re = 15,000, there are 18.42% and 17.08% increments in Num value for cube and circular hollow model surfaces in the channel with 60o fin and GO-water nanofluid compared to the channel with water flow and without fin.

Simulation of Lateral Distribution Function of Cherenkov Light in Extensive Air Showers for Yakutsk Array

The simulation of Cherenkov light Lateral distribution function (LDF) for primary particles like primary protons, Iron nuclei, Oxygen, Nitrogen, Calcium, Neutron and Argon have been performed with CORSIKA code for conditions and configuration of Yakutsk array in the energy range 1014-1016 eV for four zenith angles 0o, 5o, 10o and 15o. The results of this simulation are compared with the measurements of Yakutsk array for the same particles and energyrange

Experimental study on tribological behavior of aluminum–copper functionally graded material

A five-layered aluminum–copper metal functionally graded material was developed through powder metallurgy process. The sample comprises different weight percentages of copper and aluminum that vary from 0 wt% to 100 wt % along the thickness direction. Erosion wear was performed on air jet erosion testing apparatus at a constant impact angle of 90o and impact velocity of 151 m/s. It was observed that erosion wear decreases when there is an increase in copper content. Layer 1 comprising 100 wt% of copper has shown 76.92% lower wear compared to layer 5 (100 wt% of aluminum). Besides, erosion resistance was enhanced at graded layers due to the formation of Al2Cu phase during sintering. Abrasive wear of metal functionally graded material was evaluated on the pin-on-disc test apparatus. Experiments were conducted at different loading conditions on various abrasive surfaces (P120, P800, and P2000). Irrespective of abrasive surface, the specific wear rate of aluminum–copper metal functionally graded material sample increased with an increase in load from 5N to 15N. At 5N, abrasive wear of metal functionally graded material on P2000 grit surface was 87.7% and 27.19% lower compared to P120 and P800, respectively. Eroded and worn-out surfaces were examined microscopically to understand the wear mechanisms and are discussed in detail.

Parametric optimization of curved-rectangular shaped magnetorheological finishing tool for external cylindrical surfaces

Finishing of cylindrical surfaces in nano-scale roughness level is important to improve the surface structure of various industrial components. The nanofinishing not only enhances the surface quality but also improve the durability and reliability the components. In the present research, a new tool is developed i.e. curved-rectangular shaped magnetorheological finishing tool which is used for precise finishing of cylindrical materials made of non-ferromagnetic materials. The tool consists of two set of magnetic arrangement which is fixed at an angle of 90o by means of a tool bracket. The magnets placed inside the cylindrical bush moves to and fro as per the circumferential of workpiece. To check the performance of this tool, the design of experiments using design expert software is conducted with different process parameters i.e. workpiece rotational speeds (400 rpm, 600 rpm and 800 rpm), mesh sizes of SiC abrasives (600, 800 and 1000) and mesh sizes of EIPs (200, 300 and 400) against the percentage change in surface roughness value. The results concluded that the higher material removal in terms of Ra value as 77% is found with workpiece rotational speed 400 rpm followed by 600 mesh size of SiC abrasives and 200 mesh size of EIPs with finishing time as 40 minutes.

Evaluation of dose calculation accuracy of a commercial radiotherapy treatment planning system for adjacent radiation fields

Abstract Background: Adjacent radiation fields are applied in some radiotherapeutic cases. When using these radiation fields, considerable dose errors across the junction of radiation fields are possible. Therefore, it is necessary to evaluate the accuracy of the dose calculated by treatment planning system (TPS) when using the adjacent radiation fields. The present study aimed to quantify the dose calculation accuracy of ISOgray TPS for the photon-photon adjacent fields. Materials and methods: To assess the accuracy of dose calculations, the dose profiles were first measured by a Semiflex ionization chamber at 1, 1·5, 5 and 10 cm depths for different field sizes (6 × 6, 10 × 10 and 20 × 20 cm2), source to surface distances (SSDs) (90, 100 and 110 cm) and beam angles (0º, 15º, 30º and 45º). In the second step, the data at corresponding depths were extracted from the ISOgray TPS. Finally, the dosimetric performance of TPS was evaluated using a gamma index analysis. Results: The overall dose calculation accuracy of ISOgray TPS was within the acceptable range for the build-up region (with acceptance criteria of dose difference (DD) = 15% and distance to agreement (DTA) = 3 mm) and the depths after the build-up region (with acceptance criteria of DD = 5% and DTA = 3 mm). Moreover, the overall accuracy of dose calculations was not affected by the field size and the SSD. It was also shown that the accuracy of dose calculations was similar for the adjacent radiation fields with beam angles of 0º, 15 º and 30 º, while a considerable decrease in the pass rate values is obtained for the adjacent radiation field with 45 º beam angle. A more detailed analysis of the findings revealed that the accuracy of dose calculations in the match line regions of the adjacent radiation fields for 1 cm beam profiles was within the acceptable range; however, it declined for other depths. Conclusions: The findings showed that the overall dose calculation accuracy of ISOgray TPS was acceptable for evaluated adjacent radiation fields. However, the accuracy of dose calculations in the match line regions of the adjacent radiation fields for the depth after build-up was not within the acceptable range.

MEDIA INFORMASI BERBASIS AUGMENTED REALITY PADA KOMPLEKS MASJID AGUNG KERATON BUTON MENGGUNAKAN ALGORITMA FAST CORNER DETECTION

<p><em>The Great Mosque of the Buton Palace was built in 1917 by Sultan Sakiudin Durul Alam and is a very important area and has historical value during the Buton Sultanate. This mosque is located within the Buton Palace Fortress area (Wolio Fort). The lack of knowledge about the area is caused by very little written information about the Buton Palace Grand Mosque Complex. The purpose of this research is to design and build an information media based on Augmented Reality so that it becomes informative media for the public. This Information Media uses Augmented Reality technology with the FAST Corner Detection Algorithm. From the research that has been done, Augmented Reality technology using the FAST Corner Detection Algorithm gets good results when used as an information medium and its application on Android devices. The results are proven through accuracy testing with a distance of 10cm - 100cm and an angle of 45o - 90o with an accuracy of 10cm-20cm which is not successful and 30cm-100cm is successful and there is a delay.</em></p>

DETERMINATION OF THERMAL EFFICIENCY AND COOKING POWER OF PARABOLIC SOLAR CONCENTRATING SYSTEM WITH THERMAL COMPENSATOR FOR DOMESTIC APPLICATIONS

Energy and the environment have a strong relationship. The production and consumption of energy is one of the biggest causes of environmental damage on earth. Therefore, the rapid increase in the level of CO2 and other greenhouse gases are given out during burning fossil fuel rise or unsteady of fuel prices are the main purposes led to a search to more effectively utilize a different sources of renewable energy. To reduce the consequences of greenhouse gases emitted by burning fuel for energy, which course depletion of the ozone layer and global warming. Therefore, the use of solar radiation directly as a source of energy has proved in the past to be less economical and affordable. The paper was aimed at determination of the performance of a parabolic solar concentrating system with a thermal compensator for domestic applications using thermal efficiency and cooking power. The parabolic dish solar collector (PDSC) with a focal point of 6.15 m, aperture area of 5.8 m2 and rim angle (φo) of 45O was designed and constructed for the determination of the variables. The PDSC was made of stainless steel reflector sheet in such a way that both the manufacturing and assembly method do not require complicated skilled techniques and cost. Since the PDSC is for high temperature steam generation, hot water and cooking application. A finite element stress test analysis was conducted to determine the thermal efficiency and cooking power of the system under various weather conditions. A simple manual solar tracking mechanism was employed, and the results of the system performance were also reported. The efficiency according to thefinding depends on the optical properties of the materials involved, the geometry of the collector, and the various imperfections arising from the construction of the collector. The thermal efficiency and cooking power of the system were determined and obtained to be 54.4% and 543.1W respectively.

تأثير عوامل التشغيل على جودة الضرب لألرز طويل الحبة

The current study aimed to test and evaluate sheets’ different perforation shapes, brake angles, and milling durations to improve the quality of long-grain white rice from an abrasive milling machine. The investigated parameters of head rice yield, broken rice percentage, whitening degree, and rice bulk temperature were influenced by five sheets with five perforated shapes (horizontal, vertical, inclined, 1 mm round holes, and 1.5 mm round holes), three brake angles (0, 45, and 90º), and four milling durations (60, 70, 80, and 90 s). The results showed that the horizontal rectangular perforated sheet resulted in the highest value of head rice yield and the lowest value of broken rice. On the other hand, the vertical rectangular perforated sheet resulted in the highest whitening degree, followed by the inclined rectangular perforated sheet. The round holes (1.0 mm and 1.5 mm diameter) are not recommended for the long-grain whitening process because of the resulting high values of broken kernels, rice bulk temperature after the whitening process, and lower values of whitening degree. The brake angle of 90º resulted in the highest value of broken rice for all studied perforated sheets used in this study. This study recommended that the optimum operating conditions were using the horizontal rectangular perforated sheet, zero degree brake angle and milling duration of 80 s.

Cultivation of one-year poplar plants rooted in autumn and spring with the use of different methods of cutting planting material

Purpose. Study of the peculiarities of growing one-year cutting seedlings of four cultivars of the black poplar under the conditions of the Right Bank Forest Steppe using cuttings with a perpendicular and oblique section.
 Methods. Field, laboratory, statistical.
 Results. Cuttings of cultivars ‘Dorskamp’, ‘I-45/51’, ‘Robusta’ and Toropohrytskyi’s poplar 20 cm long were planted in November and early April for three years. The cuttings for rooting were cut from one-year-old shoots using secateurs, with cuts (i) perpendicular to the axis of the shoots and (ii) an angle of 45º. In an average of 3 years, autumn planting of the varieties ‘I-45/51’ (by 6%) and ‘Robusta’ (by 25%) showed better rooting of cuttings with perpendicular cuts. Cuttings of ‘Dorskamp’ variety with oblique cuts rooted by 11 % and Toropohrytskyi’s poplar by 7% better. When planted in spring, the rooting index of cuttings with a perpendicular cut in the ‘Dorskamp’ variety was 24% higher, in ‘I-45/51’ by 30% higher, and in ‘Robusta’ variety 54 % higher. Cuttings with an oblique cut rooted better in Toropohrytskyi’s poplar (by 20 %). The height of the rooted cuttings was the largest for autumn planting of the same variety (192.9 cm). Also, cuttings with an oblique cut had an advantage in height in the variety ‘Dorskamp’ (by 12%). In the varieties ‘I-45/51’ and ‘Robusta’, cuttings with a perpendicular cut had a higher height by 16 and 5 %, respectively. For spring planting, plants of the ‘Dorskamp’ variety had a maximum height, both when using cuttings with a perpendicular cut (197.9 cm), and with an oblique cut (195.6 cm). Plants of the ‘I-45/51’ variety with a perpendicular cut had a height of 149.1 cm and oblique 126.5 cm. In ‘Robusta’, cuttings with an oblique cut were 8% smaller. The cuttings of Toropohrytskyi’s poplar at both planting seasons were taller than cuttings with an oblique cut.
 Conclusions. The effectiveness of using cuttings with a perpendicular or oblique cut depends on the cultivar of poplar, the timing of planting and the weather conditions during vegetation season. In the conditions of the Right Bank Forest Steppe, for the cultivation of Toropohrytskyi’s poplar, it is recommended to use autumn planting of cuttings with an oblique cut. Cuttings of the varieties ‘I-45/51’ and ‘Robusta’ should be planted in autumn using a perpendicular cut, and ‘Dorskamp’ with the same cut, but in spring.

Study on Solid Particle Erosion Studies of Stellite-6 HVOF Coating on Titanium Alloy

The present research work explores the possibility of use of HVOF sprayed cermet coating Stellite-6 on gas turbine material Titanium Alloy (Ti-31). The coating is investigated for their resistance to erosion under laboratory conditions. Solid particle erosion studies were conducted using silica sand as the erodent. Erosion studies were done with impact angles of 30º, 60º and 90º. Stellite-6 coating performs better under sand erosion conditions. Stellite-6 coatings undergo damage by brittle mode. Erosion behavior of the substrate materials is ductile and resistance is better than the coating material. SEM microstructures were used for scar produced by the erodent, at 30º, 60º and 90º. impact angles, also indicates that the material damage is due to ploughing and entrapment of silica particles.

Alat Tanam Jagung dengan Kontrol Jarak Tanam dan Kualitas Biji Berdasarkan Ukuran

A corn planting tool has been made by controlling spacing and seed quality based on size. The aim of this research is to make a prototype corn planting tool with plant spacing and seed quality control based on microcontroller controlled size. The research method starts from making a prototype, and measuring system performance. The results of measuring the performance of the tool are indicated by an error in the reading of the HC-SR04 ultrasonic sensor at a point of 2 cm with an error value of 10% which is close to the actual measurement value, while for reading the distance on the ultrasonic sensor at a point > 2 cm it can be said to be constant to the actual distance. The test results of the BTS7960 motor driver work according to the system work description and are able to control the pulse width modulation (PWM) and the direction of rotation of the DC motor properly. The 28BYJ-48 stepper motor can operate the seed rationing system properly and accurately to rotate the motor at an angle of 90o takes 30 seconds. Overall the tool can function properly. Suggestions for further research, can be added monitoring of corn planting results based on the Internet of Things (IoT).

Application parameters of water transfer printing on wood-based panel surfaces

Optimum application values of the Water Transfer Printing (WTP) technique were determined on various wood-based panel surfaces. For this purpose, 8-mm-thick, glossy white, acrylic-coated medium-density fiberboard (MDF) panels (high gloss panels), polyvinyl chloride (PVC)-coated MDF panels, MDF Lam ready-to-use panels, and cellulosic, polyurethane, acrylic, and water-based paint applied MDF panels were used. An automatic immersion system with pool was designed and produced. A 30-μm-thick carbon patterned WTP film was applied on sample panel surfaces prepared with the help of this device at four immersion angles (0º, 15º, 30º, and 45º), four immersion speeds (50 cm/min, 100 cm/min, 150 cm/min, and 200 cm/min), and four immersion times (5 to 10 s, 20 to 30 s, 50 to 60 s, and 80 to 90 s). The optimum parameters of the WTP technique regarding the temperature and relative humidity of the application environment, water temperature, laying method, dissolution time, amount of activator, spray gun angle and tip clearance, air pressure, as well as immersion angle, speed, and time were determined using the measurement and observation method. According to the optimum parameters obtained in the study, the WTP technique was successfully applied to all wood-based panel surfaces.

Numerical Study of Sedimentation and Flow Pattern at the Open Channel Intake

Generally, open channel lateral intake structures are extensively used in the water and environmental projects. The passing flow at side intakes is mostly turbulence containing vertical and horizontal spiral currents causing sediment problems. The flow separation region in the intake channel is critical for sediment and water distribution during the diversion. It denotes a large reduction in the possible breadth of the lateral branch's incoming flow, as well as a place where sediment has collected, obstructing the deviated flow. This study aims to reduce and control sediment problems at the lateral intake by improving the flow pattern at this area using three-dimensional numerical models simulated in CFD, ANSYS Fluent software. The correctness of the three-dimensional numerical model was validated by a previous experimental study that showed good accuracy. Different discharge ratios and a range of shape designs were used to simulate the flow pattern at the intake channel junction. The findings demonstrated that the separation zone measurements minimize as the discharge ratio increases. Based on the changing the intake entrance shape results, cutting the outer boundary of the canal entrance widens the separation area, as well as an additional separation spot as the cutting size grows. In contrast with the internal chamfered angle models of the intake inlet, the separation area dimensions are reduced. The chamfered and rounded inner intake edge model with 30o angle to the main channel flow direction and the length of the chamfered side that normal to the flow direction (c value ) equal to three-quarters of the intake width was noticed to be the best design for lessening separation extent in this study. Thereby, the reduction ratio of the separation area width and length reaches in this case to 90% and 72%, respectively.

The Müller-Lyer illusion through mental imagery

Previous studies have pointed to a link between visual perception and mental imagery. The present experiment focuses on one of the best-known illusions, the Müller-Lyer illusion, now reproduced under conditions of real perception and by means of imagery. To that purpose, a tailored ad-hoc set of combined figures was presented to a total of 161 fine art students (M age = 20,34, SD = 1,75) who individually worked with two different variations of the Müller-Lyer figures which consisted of a 10 mm long shaft and two fins set at an angle of 30º, being 15 mm long in one instance and 45 mm long in the other. In small groups, participants also completed an image control questionnaire. Results yielded that the longer the oblique lines, the larger the magnitude of the illusion both in the situation of real perception and in the imaginary situation. Also, the magnitude of the illusion augmented in the situation of perception in contrast to the imaginary situation, both with 15 mm long fins and with those of 45 mm. However, no significant differences were found in the magnitude of the illusion between high and low individuals in image control, although interactions between image control and other variables were indeed significant. The consistency of the outcome is a step forward in the study of illusions through mental images and opens the door to new lines of research that could involve innovative methods of analysis, different versions of the illusion and wider groups of participants.

Comparative Evaluation Of Cyclic Fatigue Resistance Of Protaper NEXT And Reciproc R Rotary Files In Simulated Canals With Angle Of Curvatures At 45° And 60°: An Invitro Study

Aim: To evaluate the cyclic fatigue resistance of Pro Taper NEXT & Reciproc R rotary files in simulated canals with angle of curvaturesat 45o and 60 o.Materials and Methods; This study was conducted at HKE' s S.Nijalingappa institute of dental sciences and reasearch institute,Kalaburagi. After considering the inclusion and exclusion criteria the selected samples were divided into two groups, as G1(ProTaperNEXT) and G2(RECIPROC R), further these two groups are divide into 2 subgroups.Results: The mean cyclic fatigue was significantly high in Reciproc R procedure as compared to ProTaper NEXT. Therefore ReciprocR procedure was better as compared to ProTaper NEXT.Conclusion: Cyclic fatigue resistance of Reciproc R was higher than the ProTaper NEXT.

The Effect of Electrode Angle on the Backward Directional Longitudinal Against Penetration Percentage

Shielded Metal Arc Welding (SMAW) is one of the liquid welding processes (fusion welding) that produces a homogeneous fusion of the electrode with the base metal (base metal), which is caused by an electric arc that generates high heat to melt the electrode and base metal (base metal). simultaneously and protected by a shielding gas from the chemical reaction of the electrode flux. The depth of fusion formed is determined by the heat input, the electrode angle and the welding direction. The research was conducted at the Mechanical Engineering Laboratory of the Padang Institute of Technology. The base metal used is low carbon steel ST 37 with a thickness of 10 mm and a length of 100 mm. width 100 mm. Welding is carried out on the surface of the base metal in the flat position, the type of connection (weld type) is a surfacing weld with 4 welding lines, each strip having a distance of 20 mm. Weld length 100 mm. AWS E6013 electrode specifications with a diameter of 3.2 mm. SMAW welding machine AC current with a voltage of 30 V. current 85 A. The measured electrode angle between the electrode and the welding line is 75o, 85o, 90o. The backward welding direction where the electrode draws the welding fluid into the welding path and the normal arc height where the distance between the electrode and the base metal is equal to the diameter of the electrode. From the welding results, a penetration presentation will be obtained, namely the ratio of the depth of fusion to the width. The research results obtained welding speed: 2.48 mm/s for electrode angle 75o, 2.49 mm/s for electrode angle 85o and 2.51 mm/s for electrode angle 90o. Heat input for electrode angle 750 is 1015.93 J/ mm , the heat input for the electrode angle 85o is 1024.20 J/mm and the heat input for the electrode angle 90o is 1015.93 J/mm. From the comparison of the width with the depth of fusion, it is obtained; The electrode angle 85o has a penetration presentation of 9.85%, which is better in height than the electrode angle 75o, which has a penetration presentation of 8.43%, and the electrode angle 90o has a penetration presentation of 8.35%..

Profiles of Average Flow Velocity of Polar Solvent and Unprocessed Hydrocarbon in a Single Stage Symmetrical Bifurcated Channel

Flow distribution is a central subject in the processing industry, petroleum and industry, power industry amongst others. The concept of bifurcation has played key roles towards the realization of this science and engineering concept, as the application of bifurcation is identified in the human physiological system as it appears in the arterial system where it aids the distribution of blood plasma through the human system. In this study and experimental methos is used to ascertain the flow profile of water and crude oil representing polar solvent and unprocessed hydrocarbon, as they are allowed to flow through a bifurcated pipe with 10o, 20o, 30o, 40o, 50o, and 60o angles of bifurcation and a recovery volume of 100ml, 200ml, 300ml, 400ml and 500ml. The velocity profile obtained from this study has revealed the existence of a velocity range in the branched daughter channels of a symmetrical bifurcation, and the velocity range has its maximum and minimum values at the inner and outer walls of the branched daughter bifurcated channels, and the results further reveals the alternation of the maximum velocity between the inner and outer walls of the bifurcated daughter channels.

CYCLIC AND TORSIONAL FATIGUE RESISTANCE OF THREE DIFFERENT THERMALLY TREATED NICKEL-TITANIUM ROTARY INSTRUMENTS


 
 
 Background: The aim of this study was to evaluate the cyclic fatigue and torsional fatigue resistance of three thermally treated rotary instruments, such as: Logic 2 25.05 (LOG 25.05), Edge Taper Platinum 25.06 (EDT 25.06) and ProTaper Gold 25.08 (PTG 25.08).Methods: A total of 60 rotary instruments of LOG 25.05, EDT 25.06 and PTG 25.08 were used (n=20). Cyclic fatigue tests were performed at 36°C using an artificial stainless steel canal with a 60o angle and a 5-mm radius of curvature. The time (in seconds) and number of cycles to fracture (NCF) was recorded. The torsional test evaluated the torque and angle of rotation to failure at 3 mm from the tip according to ISO 3630-1. The fractured surface of each fragment was observed by using scanning electron microscopy (SEM). Data were analyzed using one-way ANOVA and Holm-Sidak’s tests for multiple comparison, the level of significance was set at 5%.
 Results: EDT 25.06 had highest cyclic fatigue resistance (time and NFC), followed by LOG 25.05 and PTG 25.08 (P<0.05). There were no significantly difference between LOG 25.05 and ETP 25.06 regarding the NCF (P>0.05). In relation the torsional test, the LOG 25.05 and ETP 25.06 presented similar torque (P>0.05). The PTG presented greater torque than the other groups (P<0.05). The PTG 25.08 presented the lowest angular rotation to fracture than the other groups (P<0.05). The SEM images demonstrated typical features of cyclic and torsional fracture.
 
 

Thermo-hydraulic performance investigation of a heat exchanger tube inserted with twisted tapes modified with various twist ratio and alternate axis

This paper presents a numerical investigation on a heat transfer enhancement by using a computational fluid dynamics software. The heat transfer enhancement is implemented by inserting twisted tape into a heat exchanger tube. The twisted tapes with twist ratios of 4, 6 and 8 were modified with alternate axis. The pitch of the twisted tape having the rotation direction such as clockwise and counterclockwise are connected with 90º connection angle. Water is selected as working fluid and turbulent flow condition corresponding to Reynolds number ranging from 5000 to 29000 are considered in the study. The heat exchanger tube is under constant heat flux of 50 kW/m2. Numerical analysis results prove that the use of twisted tape improves thermal performance compared to smooth tube. As the twist ratio increased, the heat transfer performance and the friction loss penalty decreased. Overall results are determined with thermohydraulic performance criteria (THP). The highest THP value is obtained as 1.21 for the tube inserted with the twisted tape which has the twist ratio of 4 and alternate axis between the twist pitches at Reynolds number of 5913

A Passive Micromixer with Koch Snowflakes Fractal Obstacle in Microchannel

The passive micromixer is one of the essential devices that can be integrated into the Lab on Chip (LoC) system. Micromixer is needed to increase mixing efficiency. In this paper, two Koch fractal obstacle-based micromixer models of Secondary Snowflakes Fractal Micromixer (SSFM) and Tertiary Snowflakes Fractal Micromixer (TSFM) were designed. The effect of the Koch fractal resistance angles (15o, 30o, 45o, 315o, 330o, 345o) and the influence of the inlet (T and T-vortex) were studied in this paper using COMSOL Multiphysics numerical simulations. The results showed that the TSFM structure with a 30o angle on the T-vortex inlet is optimal. The deflection phenomena generated by the TSFM obstacle enhance the contact area between the two fluids and chaotic convection can be increased at Reynolds Number (Re) 0.05 and Re 100. This paper examines concentration curves along the channel ranging from 1 mol/L to 5 mol/L. This clearly shows that the fluid flow direction changes within the microchannel. This work provides a new design for the micromixer.